G2Cdb::Gene report

Gene id
G00001806
Gene symbol
PLP1 (HGNC)
Species
Homo sapiens
Description
proteolipid protein 1
Orthologue
G00000557 (Mus musculus)

Databases (9)

Curated Gene
OTTHUMG00000022111 (Vega human gene)
Gene
ENSG00000123560 (Ensembl human gene)
5354 (Entrez Gene)
104 (G2Cdb plasticity & disease)
PLP1 (GeneCards)
Literature
300401 (OMIM)
Marker Symbol
HGNC:9086 (HGNC)
Protein Expression
4128 (human protein atlas)
Protein Sequence
P60201 (UniProt)

Diseases (8)

Disease Nervous effect Mutations Found Literature Mutations Type Genetic association?
D00000155: Pelizaeus-Merzbacher disease Y Y (1376553) Polymorphism (P) ?
D00000155: Pelizaeus-Merzbacher disease Y Y (1376966) Unknown (?) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (1720927) Deletion (D) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (2480601) Polymorphism (P) Y
D00000195: Multiple sclerosis Y Y (7504548) Insertion (I) N
D00000155: Pelizaeus-Merzbacher disease Y Y (7509234) Insertion (I) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (7509235) Polymorphism (P) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (7539211) Polymorphism (P) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (7539212) Polymorphism (P) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (7539213) Deletion (D) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (7541731) Polymorphism (P) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (7573159) Microinsertion (MI) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (7679906) Polymorphism (P) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (7684886) Microinsertion (MI) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (7684945) Frameshift mutation (FS) Y
D00000205: Charcot-Marie-Tooth disease type 1A Y Y (8615087) Polymorphism (P) Y
D00000205: Charcot-Marie-Tooth disease type 1A Y Y (8615087) Duplication (Du) Y
D00000187: Spastic paraplegia (hereditary) Y Y (8780101) Polymorphism (P) ?
D00000155: Pelizaeus-Merzbacher disease Y Y (8786077) Polymorphism (P) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (9008538) Polymorphism (P) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (9056547) Nonsense (No) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (9106132) Unknown (?) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (9268109) Nonsense (No) Y
D00000189: Spastic paraplegia (X-linked) Y Y (9489796) Polymorphism (P) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (9633722) Duplication (Du) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (9934976) Polymorphism (P) Y
D00000189: Spastic paraplegia (X-linked) Y Y (9934976) Polymorphism (P) Y
D00000213: Spastic paraplegia type 2 (late onset) Y Y (10319897) Microinsertion (MI) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (10401787) Deletion (D) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (10425042) Single nucleotide polymorphism (SNP) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (10588103) Microinsertion (MI) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (10588103) Duplication (Du) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (10827108) Duplication (Du) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (11071483) Polymorphism (P) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (11139261) Deletion (D) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (11180600) Unknown (?) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (11536268) Duplication (Du) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (11786921) Microinsertion (MI) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (11787038) Duplication (Du) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (12601703) Polymorphism (P) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (12605435) Insertion (I) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (12605435) Deletion (D) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (12891682) Deletion (D) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (14533091) Deletion (D) Y
D00000212: Spastic paraplegia type 2 Y Y (15450775) Microinsertion (MI) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (15689360) Duplication (Du) Y
D00000166: Schizophrenia Y Y (15694262) Single nucleotide polymorphism (SNP) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (15712223) Microinsertion (MI) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (15712223) Duplication (Du) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (15712223) Deletion (D) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (15837131) Single nucleotide polymorphism (SNP) Y
D00000195: Multiple sclerosis Y Y (16130097) Microinsertion (MI) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (16380909) Duplication (Du) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (16416265) Duplication (Du) Y
D00000155: Pelizaeus-Merzbacher disease Y Y (16416265) Deletion (D) Y

References

  • PLP1 and GPM6B intragenic copy number analysis by MAPH in 262 patients with hypomyelinating leukodystrophies: Identification of one partial triplication and two partial deletions of PLP1.

    Combes P, Bonnet-Dupeyron MN, Gauthier-Barichard F, Schiffmann R, Bertini E, Rodriguez D, Armour JA, Boespflug-Tanguy O and Vaurs-Barrière C

    INSERM U 384, Faculté de Médecine, Place Henri Dunant, 63000 Clermont-Ferrand, France.

    The proteolipid protein 1 (PLP1) gene is known to be mutated in the X-linked disorders of myelin formation Pelizaeus-Merzbacher disease (PMD) and spastic paraplegia type 2. The most commonly found PLP1 mutations are gene duplications (60-70%) and point mutations (20%). About 20% of patients with a PMD phenotype do not present identified PLP1 mutation, thus suggesting genetic heterogeneity and/or undetected PLP1 abnormalities. Except the recently described MLPA screening the seven exonic regions, the currently used techniques to quantify PLP1 gene copy number do not investigate small intragenic PLP1 rearrangements. Using the multiplex amplifiable probe hybridization (MAPH) technique, we looked simultaneously for intragenic rearrangements along the PLP1 gene (exonic and regulatory regions) and for rearrangements in the GPM6B candidate gene (a member of the proteolipid protein family). We tested 262 hypomyelinating patients: 56 PLP1 duplicated patients, 1 PLP1 triplicated patient, and 205 patients presenting a leukodystrophy of undetermined origin with brain MRI suggesting a defect in myelin formation. Our results show that MAPH is an alternative reliable technique for diagnosis of PLP1 gene copy number. It allows us (1) to demonstrate that all PLP1 duplications previously found encompass the whole gene, (2) to establish that copy number changes in GPM6B and intragenic duplications of PLP1 are very unlikely to be involved in the etiology of UHL, and (3) to identify one partial triplication and two partial deletions of PLP1 in patients presenting with a PMD phenotype.

    Neurogenetics 2006;7;1;31-7

  • Heterogeneous duplications in patients with Pelizaeus-Merzbacher disease suggest a mechanism of coupled homologous and nonhomologous recombination.

    Woodward KJ, Cundall M, Sperle K, Sistermans EA, Ross M, Howell G, Gribble SM, Burford DC, Carter NP, Hobson DL, Garbern JY, Kamholz J, Heng H, Hodes ME, Malcolm S and Hobson GM

    Clinical and Molecular Genetics, Institute of Child Health, London.

    We describe genomic structures of 59 X-chromosome segmental duplications that include the proteolipid protein 1 gene (PLP1) in patients with Pelizaeus-Merzbacher disease. We provide the first report of 13 junction sequences, which gives insight into underlying mechanisms. Although proximal breakpoints were highly variable, distal breakpoints tended to cluster around low-copy repeats (LCRs) (50% of distal breakpoints), and each duplication event appeared to be unique (100 kb to 4.6 Mb in size). Sequence analysis of the junctions revealed no large homologous regions between proximal and distal breakpoints. Most junctions had microhomology of 1-6 bases, and one had a 2-base insertion. Boundaries between single-copy and duplicated DNA were identical to the reference genomic sequence in all patients investigated. Taken together, these data suggest that the tandem duplications are formed by a coupled homologous and nonhomologous recombination mechanism. We suggest repair of a double-stranded break (DSB) by one-sided homologous strand invasion of a sister chromatid, followed by DNA synthesis and nonhomologous end joining with the other end of the break. This is in contrast to other genomic disorders that have recurrent rearrangements formed by nonallelic homologous recombination between LCRs. Interspersed repetitive elements (Alu elements, long interspersed nuclear elements, and long terminal repeats) were found at 18 of the 26 breakpoint sequences studied. No specific motif that may predispose to DSBs was revealed, but single or alternating tracts of purines and pyrimidines that may cause secondary structures were common. Analysis of the 2-Mb region susceptible to duplications identified proximal-specific repeats and distal LCRs in addition to the previously reported ones, suggesting that the unique genomic architecture may have a role in nonrecurrent rearrangements by promoting instability.

    Funded by: NCRR NIH HHS: P20 RR-020173-01, P20 RR020173; NINDS NIH HHS: NS043783, R01 NS043783; Wellcome Trust

    American journal of human genetics 2005;77;6;966-87

  • Primary progressive multiple sclerosis as a phenotype of a PLP1 gene mutation.

    Warshawsky I, Rudick RA, Staugaitis SM and Natowicz MR

    Department of Clinical Pathology, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.

    We report a 49-year-old woman with a history of progressive gait disturbance, white matter disease, and cerebrospinal fluid immunoglobulin abnormalities who met criteria for primary progressive multiple sclerosis and whose son died at age 10 years of an unknown congenital neurodevelopmental disorder. Sequencing of the proteolipid protein 1 gene showed a novel mutation, Leu30Arg (c.89TG), in the mother and son. Pelizaeus-Merzbacher disease is the cause of death in the son and explains the mother's adult-onset neurological disorder. This case goes against dogma that mothers of severely affected sons are asymptomatic as adults and expands the differential diagnosis of primary progressive multiple sclerosis to include proteolipid protein 1 gene mutations.

    Annals of neurology 2005;58;3;470-3

  • Three or more copies of the proteolipid protein gene PLP1 cause severe Pelizaeus-Merzbacher disease.

    Wolf NI, Sistermans EA, Cundall M, Hobson GM, Davis-Williams AP, Palmer R, Stubbs P, Davies S, Endziniene M, Wu Y, Chong WK, Malcolm S, Surtees R, Garbern JY and Woodward KJ

    Clinical and Molecular Genetics, Institute of Child Health, London, UK.

    We describe five boys from different families with an atypically severe form of Pelizaeus-Merzbacher disease (PMD) who have three, and in one case, five copies of the proteolipid protein (PLP1) gene. This is the first report of more than two copies of PLP1 in PMD patients and clearly demonstrates that severe clinical symptoms are associated with increased PLP1 gene dosage. Previously, duplications, deletions and mutations of the PLP1 gene were reported to give rise to this X-linked disorder. Patients with PLP1 duplication are usually classified as having either classical or transitional PMD rather than the more rare severe connatal form. The clinical symptoms of the five patients in this study included lack of stable head control and severe mental retardation, with three having severe paroxysmal disorder and two dying before the first year of life. Gene dosage was determined using interphase FISH (fluorescence in situ hybridization) and the novel approach of multiple ligation probe amplification (MLPA). We found FISH unreliable for dosage detection above the level of a duplication and MLPA to be more accurate in determination of specific copy number. Our finding that three or more copies of the gene give rise to a more severe phenotype is in agreement with observations in transgenic mice where severity of disease increased with Plp1 gene dosage and level of overexpression. The patient with five copies of PLP1 was not more affected than those with a triplication, suggesting that there is possibly a limit to the level of severity or that other genetic factors influence the phenotype. It highlights the significance of PLP1 dosage in CNS myelinogenesis as well as the importance of accurate determination of PLP1 gene copy number in the diagnosis of PMD and carrier detection.

    Brain : a journal of neurology 2005;128;Pt 4;743-51

  • A family-based association study of PLP1 and schizophrenia.

    Qin W, Gao J, Xing Q, Yang J, Qian X, Li X, Guo Z, Chen H, Wang L, Huang X, Gu N, Feng G and He L

    Bio-X Life Science Research Center, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030, PR China.

    Recently, proteolipid protein 1 (PLP1) has been identified as downregulated in schizophrenia by quantitative PCR and other technologies. In this work we attempted to investigate the role of PLP1 in the etiology of schizophrenia using a family based association study in 487 Chinese Han family trios. The TDT for allelic association demonstrated that, in male, a weak association was detected in SNP rs475827 with p=0.0294, suggesting that the genetic polymorphisms within PLP1 in male are likely to confer an increased susceptibility to schizophrenia in the Chinese population.

    Neuroscience letters 2005;375;3;207-10

  • Seventeen novel PLP1 mutations in patients with Pelizaeus-Merzbacher disease.

    Hübner CA, Orth U, Senning A, Steglich C, Kohlschütter A, Korinthenberg R and Gal A

    Institute of Human Genetics, University Hospital Eppendorf, Hamburg, Germany. c.huebner@uke.uni-hamburg.de

    Pelizaeus-Merzbacher disease (PMD) is a rare X-chromosomal neurodegenerative disorder that affects primarily the white matter of the central nervous system and is caused by mutations of the PLP1 (proteolipid protein 1) gene. We performed mutation analysis of 133 male patients with suspected PMD. Following SSCP analysis of all coding exons of PLP1, we found most likely pathogenic mutations (single base substitutions and small rearrangements) including 17 novel sequence variants in 21 (15.8%) patients. Most patients with missense mutations had a severe phenotype. Twelve patients (9.0%) carried a duplication of the entire gene, as demonstrated by quantitative real-time PCR, and presented with a variable clinical phenotype including mild, classical, and severe courses of disease. Two patients had large deletions, spanning approximately 115 kb, that included the PLP1 gene. In total, we identified pathogenic mutations involving PLP1 in 35 (26.3%) of the 133 patients analyzed.

    Human mutation 2005;25;3;321-2

  • Mild Pelizaeus-Merzbacher disease caused by a point mutation affecting correct splicing of PLP1 mRNA.

    Hübner CA, Senning A, Orth U, Zerres K, Urbach H, Gal A and Rudnik-Schöneborn S

    Institute for Human Genetics, University Hospital Eppendorf, Hamburg, Germany.

    We describe a 28-year-old male patient with a mild course of Pelizaeus-Merzbacher disease (PMD) who presented with developmental delay in his second year of life and was able to walk until 12 years of age. Several computed tomography scans in infancy and youth were normal, the diagnosis of PMD was eventually suggested by magnetic resonance imaging at the age of 24 years. Analysis of the proteolipid protein gene (PLP1) revealed a nucleotide exchange (c.762G>T) at the 3' border of exon 6, which did not entail an amino acid exchange but adversely affected splicing. PCR analysis of fibroblast cDNA showed that c.762G>T resulted in partial skipping of exon 6 in the PLP1 mRNA. Exclusion of exon 6 does not alter the reading frame but leads to absence of amino acids 232-253 that constitute a main part of the fourth transmembrane helix of the PLP protein. Remarkably, residual wild-type splicing was also detected in the patient's cultured fibroblasts. This might explain the mild phenotype in this case, as exon 6 skipping mutations resulted in a severe course of disease in other patients.

    Neuroscience 2005;132;3;697-701

  • A case of complicated spastic paraplegia 2 due to a point mutation in the proteolipid protein 1 gene.

    Lee ES, Moon HK, Park YH, Garbern J and Hobson GM

    Department of Pediatrics, Yeungnam University Hospital, Daegu, South Korea.

    Pelizaeus-Merzbacher disease (PMD) is a rare X-linked dysmyelinating disorder resulting from mutation of the proteolipid protein gene (PLP1). Clinical features of PMD include progressive psychomotor developmental delay, nystagmus, spastic quadriplegia, dystonia, and cerebellar ataxia. PMD is clinically classified into three subtypes according to the severity of the disease: connatal, transitional, and classic forms. Patients with PMD have been identified with duplication, point mutations, and deletion of PLP1. In addition, spastic paraplegia 2 (SPG2) is allelic to PMD and typically caused by missense mutations in the second extracellular domain of PLP1 or in the PLP1-specific region that is spliced out during formation of the DM20 isoform. The authors describe a Korean boy diagnosed with SPG2 caused by a mutation that results in a Pro215Leu substitution in the second extracellular domain. Analysis of phenotypes resulting from mutations affecting PLP1 has been valuable in identifying functional domains of this still incompletely understood major myelin protein. Null mutations and mutations affecting the PLP1-specific domain cause peripheral neuropathy. The PLP1-specific domain also is important in the long-term maintenance of axonal integrity. This patient's phenotype was relatively mild, in contrast with other mutations at position 215 of PLP1 that cause severe PMD. One of these severe mutations is also a missense mutation substituting an aliphatic residue, alanine, for proline. The distinct severity difference between the Pro215Leu and Pro215Ala substitutions suggests that this region of the protein is very sensitive to subtle structural changes and likely plays a critical role in PLP1 function.

    Journal of the neurological sciences 2004;224;1-2;83-7

  • [Duplication of the PLP gene and the classical form of Pelizaeus-Merzbacher disease].

    Blanco-Barca MO, Eirís-Puñal J, Soler-Regal C and Castro-Gago M

    Servicio de Neuropediatría, Departamento de Pediatría, Hospital Clínico Universitario, Santiago de Compostela, España.

    Introduction: Pelizaeus-Merzbacher disease (PMD) is a rare form of sudanophilic leukodystrophy which is transmitted by recessive inheritance linked to the X chromosome. It only affects the myelin of the central nervous system (CNS) and is caused by a proteolipid protein (PLP) deficit, which is coded for in Xq21.2-q22. Presentation follows a classical or connatal pattern and is associated with nystagmus, stridor and pyramidal/extrapyramidal manifestations within the framework of a clinical picture of psychomotor retardation and regression with variable clinical course and presentation.

    A 37-month-old male, with sever psychomotor retardation, nystagmus and choreoathetotic movements with a stationary developmental profile. An MRI scan of the brain showed severe supratentorial hypomyelination and peripheral electrophysiological explorations (EMG and NCS) were normal. The genetic study using PCR revealed duplication in the PLP gene.

    Conclusion: This observation corresponds to a classical form of PMD, which must be taken into account when associated with: 1) Psychomotor retardation; 2) Early nystagmus; 3) Pyramidal/extrapyramidal involvement; 4) Absence of peripheral neurophysiological involvement; 5) A neuroradiological pattern of hypomyelination of the CNS.

    Revista de neurologia 2003;37;5;436-8

  • Myelination of a fetus with Pelizaeus-Merzbacher disease: immunopathological study.

    Shiraishi K, Itoh M, Sano K, Takashima S and Kubota T

    Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan.

    We report an autopsied case of a 21-gestational-week fetus with duplication of the proteolipid protein (PLP) gene (PLP1). An immunohistochemical study, which can detect the specific expression of PLP, myelin basic protein, myelin-associated glycoprotein, and platelet-derived growth factor receptor alpha subunit in brain tissues, showed that the myelination was almost the same as that of age-matched controls. This result suggests that the development and migration of the oligodendrocyte is normal in Pelizaeus-Merzbacher disease until midgestation. To our knowledge, this is the first report of the myelination of a fetus with duplication of the PLP1 gene.

    Annals of neurology 2003;54;2;259-62

  • Complex chromosomal rearrangement and associated counseling issues in a family with Pelizaeus-Merzbacher disease.

    Woodward K, Cundall M, Palmer R, Surtees R, Winter RM and Malcolm S

    Clinical and Molecular Genetics Unit, Institute of Child Health, London, United Kingdom. k.woodward@ich.ucl.ac.uk

    We report cytogenetic and molecular findings in a family in which Pelizaeus-Merzbacher disease has arisen by a sub-microscopic duplication of the proteolipid protein (PLP1) gene involving the insertion of approximately 600 kb from Xq22 into Xq26.3. The duplication arose in an asymptomatic mother on a paternally derived X chromosome and was inherited by her son, the proband, who is affected with Pelizaeus-Merzbacher disease. The mother also carries a large interstitial deletion of approximately 70 Mb extending from Xq21.1 to Xq27.3, which is present in a mosaic form. In lymphocytes, the mother has no normal cells, having one population with three copies of the PLP1gene (one normal X and one duplication X chromosome) and the other population having only one copy of the PLP1 gene (one normal X and one deleted X chromosome). Her karyotype is 46,XX.ish dup (X) (Xpter --> Xq26.3::Xq22 --> Xq22::Xq26.3 --> Xqter)(PLP++)/46,X,del(X)(q21.1q27.3).ish del(X)(q21.1q27.3)(PLP-). Both ends of the deletion have been mapped by fluorescence in situ hybridization using selected DNA clones and neither involves the PLP1 gene or are in the vicinity of the duplication breakpoints. Prenatal diagnosis was carried out in a recent pregnancy and the complex counseling issues associated with these chromosomal rearrangements are discussed.

    American journal of medical genetics. Part A 2003;118A;1;15-24

  • Schwann cell expression of PLP1 but not DM20 is necessary to prevent neuropathy.

    Shy ME, Hobson G, Jain M, Boespflug-Tanguy O, Garbern J, Sperle K, Li W, Gow A, Rodriguez D, Bertini E, Mancias P, Krajewski K, Lewis R and Kamholz J

    Department of Neurology and Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA.

    Proteolipid protein (PLP1) and its alternatively spliced isoform, DM20, are the major myelin proteins in the CNS, but are also expressed in the PNS. The proteins have an identical sequence except for 35 amino acids in PLP1 (the PLP1-specific domain) not present in DM20. Mutations of PLP1/DM20 cause Pelizaeus-Merzbacher Disease (PMD), a leukodystrophy, and in some instances, a peripheral neuropathy. To identify which mutations cause neuropathy, we have evaluated a cohort of patients with PMD and PLP1 mutations for the presence of neuropathy. As shown previously, all patients with PLP1 null mutations had peripheral neuropathy. We also identified 4 new PLP1 point mutations that cause both PMD and peripheral neuropathy, three of which truncate PLP1 expression within the PLP1-specific domain, but do not alter DM20. The fourth, a splicing mutation, alters both PLP1 and DM20, and is probably a null mutation. Six PLP1 point mutations predicted to produce proteins with an intact PLP1-specific domain do not cause peripheral neuropathy. Sixty-one individuals with PLP1 duplications also had normal peripheral nerve function. These data demonstrate that expression of PLP1 but not DMSO is necessary to prevent neuropathy, and suggest that the 35 amino acid PLP1-specific domain plays an important role in normal peripheral nerve function.

    Funded by: NINDS NIH HHS: R01 NS043783

    Annals of neurology 2003;53;3;354-65

  • A severe connatal form of Pelizaeus Merzbacher disease in a Czech boy caused by a novel mutation (725C>A, Ala242Glu) at the 'jimpy(msd) codon' in the PLP gene.

    Seeman P, Paderova K, Benes V and Sistermans EA

    Department of Child Neurology, Second School of Medicine, Charles University and University Hospital Motol, Prague, 150 06 Prague 5, Czech Republic. pavel.seeman@lfmotol.cuni.cz

    Pelizaeus Merzbacher disease (PMD) is an X-linked recessive disorder of the central nervous system myelination caused by mutations involving the proteolipid protein gene (PLP). Early nystagmus and developmental delay, progressive pyramidal, cerebellar and dystonic signs as well as white matter changes in brain MRI are typical for PMD. The PLP gene can be affected by two major types of mutations. A duplication of the whole PLP gene is the most common mutation and results usually in the milder classical phenotype, whereas point mutations in PLP gene often result in the rarer and more severe connatal form of PMD. The PLP protein is a higly conserved across species and is identical in human, mouse and rat. We describe a 13-year-old Czech boy with an early and severe developmental delay. His maternal uncle died at the age of one year and was also early and severely psychomotoricly retarded. The patient was the first child of healthy unrelated parents born after an uneventful pregnancy and delivery in 1988. Hyperbilirubinemia and bronchopneumonia and early stridor complicated his neonatal period. Diffuse hypotonia, nystagmus, psychomotor retardation, visual and hearing impairment have been observed in the patient since the age of 6 weeks. White matter abnormalities, cortical and periventricular atrophy were detected by MRI at the age of 6 and 11 years, respectively. Despite these signs and results an accurate clinical diagnosis was unclear until the age of 11 years. Last neurological examination in 1999 showed no nystagmus anymore, but extremely dystrophic limbs, truncal deformation, due to severe scoliosis, tetraplegia with hyperreflexia in C5C7 and areflexia L2S2 and positive pyramidal signs. The boy had no visual or speech contact. DNA tests followed the clinical suspicion for PMD. At first, duplication of PLP gene was excluded by quantitative comparative PCR. Direct sequencing of PLP gene detected a novel mutation in exon 6, a missense mutation 725C-->A (Ala242Glu) in the patient and in his mother and later also in his maternal grandmother. The same codon, but to valine (Ala242Val) is mutated in jimpy(msd) mouse, which is the frequently used animal model for PMD. Prenatal diagnosis for the next pregnancy has been offered to the family. The patient died recently at the age of 13 years due to respiratory failure. Our results support the data on the importance of this conserved amino acid alanine at codon 242.

    International journal of molecular medicine 2002;9;2;125-9

  • Prenatal interphase FISH diagnosis of PLP1 duplication associated with Pelizaeus-Merzbacher disease.

    Inoue K, Kanai M, Tanabe Y, Kubota T, Kashork CD, Wakui K, Fukushima Y, Lupski JR and Shaffer LG

    Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.

    A submicroscopic genomic duplication in Xq22.2 that contains the entire proteolipid protein 1 gene (PLP1) is responsible for the majority of Pelizaeus-Merzbacher disease (PMD) patients. We previously developed an interphase FISH assay to screen for PLP1 duplications in PMD patients using peripheral blood and lymphoblastoid cell lines. This assay has been utilized as a clinical diagnostic test in our cytogenetics laboratory. To expand usage of the interphase FISH assay to prenatal diagnosis of PLP1 duplications, we examined three PMD families with PLP1 duplications utilizing aminiotic fluid samples. In two families the FISH assay revealed fetuses with PLP1 duplications, whereas the other fetus showed a normal copy number of PLP1. Haplotype analyses, as well as an additional FISH analysis using postnatal blood samples, confirmed the results of the prenatal analyses. Our study demonstrates utility of the interphase FISH assay in the prenatal diagnosis of PLP1 duplications in PMD.

    Funded by: NICHD NIH HHS: P30 HD24064; NINDS NIH HHS: R01 NS27042

    Prenatal diagnosis 2001;21;13;1133-6

  • Prenatal diagnosis of Pelizaeus-Merzbacher disease: detection of proteolipid protein gene duplication by quantitative fluorescent multiplex PCR.

    Regis S, Filocamo M, Mazzotti R, Cusano R, Corsolini F, Bonuccelli G, Stroppiano M and Gatti R

    Laboratorio di Diagnosi Pre e Postnatale di Malattie Metaboliche, Istituto G. Gaslini, Largo G. Gaslini 5, 16147 Genoa, Italy. dppm@ospedale-gaslini.ge.it

    A prenatal diagnosis of Pelizaeus-Merzbacher disease (PMD) resulting from proteolipid protein gene (PLP) duplication was performed by a quantitative fluorescent multiplex PCR method. PLP gene copy number was determined in the proband, the pregnant mother, the male fetus and two aunts. Small amounts of genomic DNA extracted from peripheral blood and from chorionic villi were used. The fetus, in common with the proband, was identified as PMD-affected being a carrier of the PLP gene duplication, inherited from the mother, while the two aunts were non-carriers. The data obtained were confirmed by segregation analysis of a PLP-associated dinucleotide-repeat polymorphism amplified by the same multiplex PCR.

    Prenatal diagnosis 2001;21;8;668-71

  • A new polymorphism in the proteolipid protein (PLP1) gene and its use for carrier detection of PLP1 gene duplication in Pelizaeus-Merzbacher disease.

    Hobson G, Stabley D, Funanage V and Marks H

    Department of Research, Alfred I. DuPont Hospital for Children, Wilmington, DE, USA. ghobson@nemours.org

    Pelizaeus Merzbacher Disease (PMD) is an X-linked recessive dysmyelinating disorder of the central nervous system. Most patients have point mutations in exons of the proteolipid protein (PLP1) gene or duplication of a genomic region that includes the PLP1 gene. We identified a common MspI polymorphism in intron 1 of the PLP1 gene and used it to determine carrier status for PLP1 gene duplication in PMD by using a quantitative PCR approach.

    Human mutation 2001;17;2;152

  • A novel deletion (c663delC) at exon 5 of the proteolipid protein gene in Pelizaeus-Merzbacher disease.

    Matsumura T, Osaka H, Inoue K, Sugiyama N, Onishi H, Yamada Y, Hayashi M and Kosaka K

    Department of Psychiatry, School of Medicine, Yokohama City University, Tokyo, Japan.

    Human mutation 2001;17;1;80

  • Mutations in noncoding regions of the proteolipid protein gene in Pelizaeus-Merzbacher disease.

    Hobson GM, Davis AP, Stowell NC, Kolodny EH, Sistermans EA, de Coo IF, Funanage VL and Marks HG

    Department of Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19899, USA. ghobson@nemours.org

    Background: Pelizaeus-Merzbacher disease (PMD) is an X-linked recessive dysmyelinating disorder of the CNS. Duplications or point mutations in exons of the proteolipid protein (PLP) gene are found in most patients.

    Objective: To describe five patients with PMD who have mutations in noncoding regions of the PLP gene.

    Methods: Quantitative multiplex PCR and Southern blot analyses were used to detect duplication of the PLP gene, and DNA sequence analysis, including exon-intron borders, was used to detect mutation of the PLP gene.

    Results: Duplication of the PLP gene was ruled out, and mutations were identified in noncoding regions of five patients in four families with PMD. In two brothers with a severe form of PMD, a G to T transversion at IVS6+3 was detected. This mutation resulted in skipping of exon 6 in the PLP mRNA of cultured fibroblasts. A patient who developed nystagmus at 16 months and progressive spastic ataxia at 18 months was found to have a 19-base pair (bp) deletion of a G-rich region near the 5' end of intron 3 of the PLP gene. A patient with a T to C transition at IVS3+2 and a patient with an A to G transition at IVS3+4 have the classic form of PMD. These, like the 19-bp deletion, are in intron 3, which is involved in PLP/DM20 alternative splice site selection.

    Conclusions: Mutations in introns of the PLP gene, even at positions that are not 100% conserved at splice sites, are an important cause of PMD.

    Neurology 2000;55;8;1089-96

  • Additional copies of the proteolipid protein gene causing Pelizaeus-Merzbacher disease arise by separate integration into the X chromosome.

    Hodes ME, Woodward K, Spinner NB, Emanuel BS, Enrico-Simon A, Kamholz J, Stambolian D, Zackai EH, Pratt VM, Thomas IT, Crandall K, Dlouhy SR and Malcolm S

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202, USA. mhodes@iupui.edu

    The proteolipid protein gene (PLP) is normally present at chromosome Xq22. Mutations and duplications of this gene are associated with Pelizaeus-Merzbacher disease (PMD). Here we describe two new families in which males affected with PMD were found to have a copy of PLP on the short arm of the X chromosome, in addition to a normal copy on Xq22. In the first family, the extra copy was first detected by the presence of heterozygosity of the AhaII dimorphism within the PLP gene. The results of FISH analysis showed an additional copy of PLP in Xp22.1, although no chromosomal rearrangements could be detected by standard karyotype analysis. Another three affected males from the family had similar findings. In a second unrelated family with signs of PMD, cytogenetic analysis showed a pericentric inversion of the X chromosome. In the inv(X) carried by several affected family members, FISH showed PLP signals at Xp11.4 and Xq22. A third family has previously been reported, in which affected members had an extra copy of the PLP gene detected at Xq26 in a chromosome with an otherwise normal banding pattern. The identification of three separate families in which PLP is duplicated at a noncontiguous site suggests that such duplications could be a relatively common but previously undetected cause of genetic disorders.

    Funded by: NICHD NIH HHS: HD26979, P30 HD026979

    American journal of human genetics 2000;67;1;14-22

  • MR-revealed myelination in the cerebral corticospinal tract as a marker for Pelizaeus-Merzbacher's disease with proteolipid protein gene duplication.

    Takanashi J, Sugita K, Tanabe Y, Nagasawa K, Inoue K, Osaka H and Kohno Y

    Department of Pediatrics, Faculty of Medicine, Chiba University, Chiba-shi, Japan.

    Pelizaeus-Merzbacher's disease (PMD) is caused by mutations in the proteolipid protein (PLP) gene. Recent studies have shown that an increased PLP dosage, resulting from total duplication of the PLP gene, invariably causes the classic form of PMD. The purpose of this study was to compare the MR findings of PMD attributable to PLP duplication with those of PMD arising from a missense mutation.

    Methods: Seven patients with PMD, three with a PLP missense mutation in either exon 2 or 5 (patients 1-3), and four with PLP duplication (patient 4 having larger PLP duplication than patients 5-7) were clinically classified as having either the classic or connatal form of PMD. Cerebral MR images were obtained to analyze the presence of myelination and T1 and T2 shortening in the deep gray matter. Multiple MR studies were performed in six of the seven patients to analyze longitudinal changes.

    Results: Four patients (patients 1-4) were classified as having connatal PMD, whereas the other three (patients 5-7) were classified as having classic PMD. Myelination in the cerebral corticospinal tract, optic radiation, and corpus callosum was observed in three cases of classic PMD with PLP duplication. In patient 4, myelination extended to the internal capsule, corona radiata, and centrum semiovale over a 3-year period. No myelination was observed in three PMD cases with a PLP point mutation. T2 shortening in the deep gray matter was recognized in all patients with PMD.

    Conclusion: The presence of myelination in the cerebral corticospinal tract with diffuse white matter hypomyelination on MR images could be a marker for PMD with PLP duplication. It is suggested that progression of myelination may be present in connatal PMD with large PLP duplication.

    AJNR. American journal of neuroradiology 1999;20;10;1822-8

  • A novel mutation (A246T) in exon 6 of the proteolipid protein gene associated with connatal Pelizaeus-Merzbacher disease.

    Yamamoto T and Nanba E

    Gene Research Center, Tottori University, Yonago 683-8503, Japan.

    Human mutation 1999;14;2;182

  • A de novo splice donor site mutation causes in-frame deletion of 14 amino acids in the proteolipid protein in Pelizaeus-Merzbacher disease.

    Aoyagi Y, Kobayashi H, Tanaka K, Ozawa T, Nitta H and Tsuji S

    Department of Neurology, Brain Research Institute, Niigata University, Japan.

    Pelizaeus-Merzbacher disease (PMD) is a leukodystrophy associated with mutations in the proteolipid protein (PLP) gene. Jimpy is a mouse model of human PMD, and a splice site mutation in Jimpy causes the deletion of exon 5 from the PLP mRNA, producing a truncated form of PLP. We describe a de novo point mutation at the 5' splice donor site of exon 5 in a 17-year-old male with PMD, which results in the skipping of 42 base pairs of exon 5. The mutation removes only 14 amino acids in-frame of PLP. This is a novel splice donor site mutation in the human PLP gene. Moreover, the results indicate that the 14-amino acid deletion in the PLP is responsible for oligodendrocyte cell death and the development of PMD.

    Annals of neurology 1999;46;1;112-5

  • Novel exon 3B proteolipid protein gene mutation causing late-onset spastic paraplegia type 2 with variable penetrance in female family members.

    Sivakumar K, Sambuughin N, Selenge B, Nagle JW, Baasanjav D, Hudson LD and Goldfarb LG

    Medical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-1361, USA.

    Spastic paraplegia type 2 (SPG2) is allelic to Pelizaeus-Merzbacher disease (PMD), with both conditions resulting from mutations in the proteolipid protein gene (PLP). We report an SPG2 family in which 3 male members and a heterozygous female member were affected with spastic paraplegia characterized by relatively late onset and mild clinical manifestations. A unique H147Y mutation in exon 3B of the PLP altering the proteolipid protein (PLP) but not the alternatively spliced DM20 isoform was identified as the cause of this distinct disease phenotype. Cellular pathology studies of SPG2 mutations offer an explanation for the paradoxical finding that mutations associated with the mildest phenotype in male family members also affect female carriers.

    Annals of neurology 1999;45;5;680-3

  • Different mutations in the same codon of the proteolipid protein gene, PLP, may help in correlating genotype with phenotype in Pelizaeus-Merzbacher disease/X-linked spastic paraplegia (PMD/SPG2).

    Hodes ME, Zimmerman AW, Aydanian A, Naidu S, Miller NR, Garcia Oller JL, Barker B, Aleck KA, Hurley TD and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA. mhodes@medgen.iupui.edu

    Pelizaeus-Merzbacher disease/X-linked spastic paraplegia (PMD/SPG2) comprises a spectrum of diseases that range from severe to quite mild. The reasons for the variation in severity are not obvious, but suggested explanations include the extent of disruption of the transmembrane portion of the proteolipid protein caused by certain amino acid substitutions and interference with the trafficking of the PLP molecule in oligodendrocytes. Four codons in which substitution of more than one amino acid has occurred are available for examination of clinical and potential structural manifestations: Valine165 to either glutamate or glycine, leucine 045 to either proline or arginine, aspartate 202 to asparagine or histidine, and leucine 223 to isoleucine or proline. Three of these mutations, Val165Gly, Leu045Pro, and Leu223Ile have not been described previously in humans. The altered amino acids appear in the A-B loop, C helix, and C-D loop, respectively. We describe clinically patients with the mutations T494G (Val165Gly), T134C (Leu045Pro), and C667A (Leu223Ile). We discuss also the previously reported mutations Asp202Asn and Asp202His. We have calculated the changes in hydrophobicity of short sequences surrounding some of these amino acids and compared the probable results of the changes in transmembrane structure of the proteolipid protein for the various mutations with the clinical data available on the patients. While the Val165Glu mutation, which is expected to produce disruption of a transmembrane loop of the protein, produces more severe disease than does Val165Gly, no particular correlation with hydrophobicity is found for the other mutations. As these are not in transmembrane domains, other factors such as intracellular transport or interaction between protein chains during myelin formation are probably at work.

    American journal of medical genetics 1999;82;2;132-9

  • Duplication of the proteolipid protein gene is the major cause of Pelizaeus-Merzbacher disease.

    Sistermans EA, de Coo RF, De Wijs IJ and Van Oost BA

    Department of Human Genetics, University Hospital Nijmegen, The Netherlands.

    Pelizaeus-Merzbacher disease (PMD), an X-linked recessive dysmyelination disorder, is caused by mutations in the proteolipid protein (PLP) gene. However, missense mutations were only found in a fraction of PMD patients, even in families that showed linkage with the PLP locus on Xq22. Here we describe the use of an extended protocol that includes screening for both missense mutations and duplications.

    Method: Two groups of patients were analyzed, one group with 10 independent PMD families and one group with 24 sporadic patients suspected of PMD. Missense mutations in the PLP gene were identified by sequencing. PLP gene duplications were detected by quantitative polymerase chain reaction and/or Southern blot analysis.

    Results: Sequencing of the PLP gene revealed four mutations in group 1 and one mutation in group 2. However, inclusion of duplication analysis in the screening protocol raised the amount of mutations found in group 1 from 40 to 90%, and in group 2 from 4 to 25%.

    Conclusions: These results demonstrate that duplications of the PLP gene are the major cause of PMD. Furthermore, it appears that the phenotype resulting from PLP duplications is relatively mild, and that many probands are nontypical PMD patients.

    Neurology 1998;50;6;1749-54

  • X-linked spastic paraplegia due to a mutation (C506T; Ser169Phe) in exon 4 of the proteolipid protein gene (PLP).

    Hodes ME, Hadjisavvas A, Butler IJ, Aydanian A and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA. mhodes@medgen.iupui.edu

    A transition C506T was found in exon 4 of the proteolipid protein gene of a boy with spastic paraplegia. This mutation resulted in the substitution of phenylalanine for serine 169, which is in the third transmembrane domain of the proteolipid protein molecule. The mutation apparently arose de novo, as it was absent from his mother.

    American journal of medical genetics 1998;75;5;516-7

  • Family with Pelizaeus-Merzbacher disease/X-linked spastic paraplegia and a nonsense mutation in exon 6 of the proteolipid protein gene.

    Bond C, Si X, Crisp M, Wong P, Paulson GW, Boesel CP, Dlouhy SR and Hodes ME

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA.

    We report on a C-to-T transition in exon 6 of the PLP gene in a male with Pelizaeus-Merzbacher disease/X-linked spastic paraplegia. The transition changes a glutamine at amino acid residue 233 to a termination codon. This premature stop codon probably results in a truncated protein that is not functional. Six other relatives were analyzed for the mutation and two female carriers were identified. Autopsy data on one male are presented.

    Funded by: NICHD NIH HHS: 2T32HD07373

    American journal of medical genetics 1997;71;3;357-60

  • A new proteolipid lipoprotein mutation in Pelizaeus-Merzbacher disease.

    Verhagen WI, Huygen PL, Smeets HJ, Renier WO and de Wijs I

    Journal of the neurological sciences 1997;147;2;215-6

  • Nonsense mutation in exon 3 of the proteolipid protein gene (PLP) in a family with an unusual form of Pelizaeus-Merzbacher disease.

    Hodes ME, Blank CA, Pratt VM, Morales J, Napier J and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA.

    We report a G-->A transition at nucleotide 431 of the proteolipid protein gene (PLP) results in a nonsense codon in a family with an unusual form of Pelizaeus-Merzbacher disease (PMD). The mutation, which creates a second AluI restriction site, results in a nonsense mutation in PLP. The clinical picture resembles somewhat that of X-linked spastic paraplegia (SPG). It differs from this and both the classical and connatal forms of PMD in that it is relatively mild in form, onset is delayed beyond age 2 years, nystagmus is absent, tremors are prominent, mental retardation is not severe, some patients show dementia or personality disorders, the disease is progressive rather than static in some, and several females show signs of disease. The nonsense mutation, which is in exon 3B, should block the synthesis of normal PLP but spare DM20, the isoform whose persistence has been associated with mild forms of PLP-associated disease in both humans and mice.

    American journal of medical genetics 1997;69;2;121-5

  • Mutations in the proteolipid protein gene in Japanese families with Pelizaeus-Merzbacher disease.

    Inoue K, Osaka H, Kawanishi C, Sugiyama N, Ishii M, Sugita K, Yamada Y and Kosaka K

    Department of Psychiatry, Yokohama City University, School of Medicine, Japan.

    Pelizaeus-Merzbacher disease (PMD) is a rare X-linked dysmyelinating disorder of the CNS resulting from abnormalities in the proteolipid protein (PLP) gene. Exonic mutations in the PLP gene are present in 10 to 25% of all cases. In investigating genotype-phenotype correlations, we screened five Japanese families with PMD for PLP gene mutations and compared their clinical manifestations. We identified two novel nucleotide substitutions in exon 5, at V208N and at P210L, in two families. In the remaining three families, there were no mutations detected. Although all patients satisfied the criteria for the classical form of PMD, two families not carrying the mutations showed milder clinical manifestations than those with the mutations. Since linkage analysis has shown homogeneity at the PLP locus in patients with PMD, our findings suggest that there may be genetic abnormalities other than exonic mutations that cause milder forms of PMD.

    Neurology 1997;48;1;283-5

  • Refined genetic mapping and proteolipid protein mutation analysis in X-linked pure hereditary spastic paraplegia.

    Cambi F, Tang XM, Cordray P, Fain PR, Keppen LD and Barker DF

    Department of Neurology, Thomas Jefferson University, Philadelphia, PA, USA.

    X-linked hereditary spastic paraplegias (HSP) present with two distinct phenotypes, pure and complicated. The pure form is characterized by spasticity and gait difficulties but lacks the additional features (nystagmus, dysarthria, mental retardation) present in the complicated form. The complicated form is heterogeneous, caused by mutations of the L1CAM gene at Xq28 (SPG1) or the PLP gene at Xq22 (SPG2) that is allelic to Pelizaeus-Merzbacher disease (PMD). Since in one kindred (K313) the pure form of HSP was also mapped to Xq22, this raises the issue as to whether a pure form of HSP exists that is allelic to X-linked complicated HSP (SPG2) and PMD. To answer this question, we carried out linkage analysis in a new pedigree with pure HSP (K101) and refined linkage in pedigree K313. The PLP gene was also screened for mutation by direct sequencing and reverse-transcriptase polymerase chain reaction (RT-PCR). In both families, the disease locus mapped to Xq22 with Lod scores at zero recombination of 5.3 for COL4A5 2B6 in K313 and 2.4 for DXS101 in K101. A T to C transition in exon 5 of the PLP gene was identified from affected individuals of K313. This transition causes a Ser to Pro mutation in the major extracellular loop of PLP/DM20. This finding demonstrates that a form of X-linked pure spastic paraplegia, X-linked complicated HSP (SPG2) and PMD are allelic disorders. There was no evidence of mutations in either coding sequences or the intron/exon junctions of PLP in pedigree K101, suggesting that the disease-producing mutation may be in the noncoding portions of PLP or in a nearby gene.

    Funded by: NINDS NIH HHS: NS01726-02

    Neurology 1996;46;4;1112-7

  • A (G-to-A) mutation in the initiation codon of the proteolipid protein gene causing a relatively mild form of Pelizaeus-Merzbacher disease in a Dutch family.

    Sistermans EA, de Wijs IJ, de Coo RF, Smit LM, Menko FH and van Oost BA

    Department of Human Genetics, University Hospital Nijmegen, The Netherlands.

    Pelizaeus-Merzbacher disease (PMD) is an X-linked recessive disorder that is characterized by dysmyelination of the central nervous system resulting from mutations in the proteolipid protein (PLP) gene. Mutations causing either overexpression or expression of a truncated form of PLP result in oligodendrocyte cell death because of accumulation of PLP in the endoplasmic reticulum. It has therefore been hypothesized that absence of the protein should result in a less severe phenotype. However, until now, only one patient has been described with a complete deletion of the PLP gene. We report a Dutch family with a relatively mild form of PMD, in which the disease cosegregates with a (G-to-A) mutation in the initiation codon of the PLP gene. This mutation should cause the total absence of PLP and is therefore in agreement with the hypothesis that absence of PLP leads to a mild form of PMD.

    Human genetics 1996;97;3;337-9

  • Pelizaeus-Merzbacher disease caused by a de novo mutation that originated in exon 2 of the maternal great-grandfather of the propositus.

    Pratt VM, Boyadjiev S, Green K, Hodes ME and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA.

    Pelizaeus-Merzbacher disease (PMD) is an X-linked dysmyelinating disorder of the central nervous system. Many cases of PMD can be attributed to defects in the proteolipid protein gene (PLP). To date, with one exception, each family has had either no or a unique mutation in one of the seven exons of PLP. We describe a new missense mutation in exon 2 of the PLP gene of an affected individual. This mutation codes for Ile instead of Thr at codon 42. The point mutation originated in the X chromosome of the maternal great-grandfather of the propositus. This was determined from the pattern of inheritance of the AhaII polymorphism and a series of microsatellite markers that are localized near PLP at Xq22.

    American journal of medical genetics 1995;58;1;70-3

  • Girl with signs of Pelizaeus-Merzbacher disease heterozygous for a mutation in exon 2 of the proteolipid protein gene.

    Hodes ME, DeMyer WE, Pratt VM, Edwards MK and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA.

    We studied a female infant with clinical signs of Pelizaeus-Merzbacher disease (PMD), who has a familial mutation (C41-->T) in exon 2 of the proteolipid protein gene (PLP), and selected relatives. While the carrier mother and grandmother of the proposita currently are neurologically normal and show normal T2 magnetic resonance imaging (MRI) of the brain, the infant has a neurological picture, MRIs, and brain auditory evoked response (BAER) consistent with that diagnosis. The data here presented show that PMD can occur in females carrying a mutation in the PLP gene. Our experience with the MRIs of this patient, her mother and grandmother, and those of a previously reported family [Pratt et al.: Am J Med Genet 38:136-139, 1991] show that molecular genetic analysis and not MRI is the appropriate means for carrier detection.

    American journal of medical genetics 1995;55;4;397-401

  • In-frame deletion in the proteolipid protein gene of a family with Pelizaeus-Merzbacher disease.

    Kleindorfer DO, Dlouhy SR, Pratt VM, Jones MC, Trofatter JA and Hodes ME

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA.

    We describe an in-frame deletion of parts of exons 3 and 4 of the proteolipid protein gene (PLP), with all of the intervening sequence, in a 3-generation family with Pelizaeus-Merzbacher disease. The mutation removes 49 amino acids of the PLP.

    American journal of medical genetics 1995;55;4;405-7

  • Pelizaeus-Merzbacher disease in a family of Portuguese origin caused by a point mutation in exon 5 of the proteolipid protein gene.

    Pratt VM, Boyadjiev S, Dlouhy SR, Silver K, Der Kaloustian VM and Hodes ME

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA.

    Single-strand conformational polymorphism analysis of an affected male with Pelizaeus-Merzbacher disease (PMD) showed a slight change in mobility of amplified exon 5 of the proteolipid protein (PLP) gene. The exon was sequenced and a G-->A transition at codon 216 was found. This mutation eliminates a BstNI restriction site and creates a MaeI restriction site. In 1989, Gencic et al. reported a mutation that destroyed the same BstNI site, but resulted in a substitution at codon 215 [Am J Hum Genet 45:435-442]. The mutation we report here is also present in the patient's mother and her male fetus as determined by polymerase chain reaction analysis of amniocytes.

    American journal of medical genetics 1995;55;4;402-4

  • Pelizaeus-Merzbacher disease: a point mutation in exon 6 of the proteolipid protein (PLP) gene.

    Pratt VM, Dlouhy SR and Hodes ME

    Pelizaeus-Merzbacher disease has been known since 1885. It is characterized by severe dysmyelination of the central nervous system. We describe a new mutation in exon 6 of the proteolipid protein gene in a 9-year-old boy with severe connatal Pelizaeus-Merzbacher disease.

    Clinical genetics 1995;47;2;99-100

  • Charcot-Marie-Tooth disease type 1A: morphological phenotype of the 17p duplication versus PMP22 point mutations.

    Gabreëls-Festen AA, Bolhuis PA, Hoogendijk JE, Valentijn LJ, Eshuis EJ and Gabreëls FJ

    Institute of Neurology, University Hospital Nijmegen, The Netherlands.

    Charcot-Marie-Tooth disease type 1A (CMT1A) or hereditary motor and sensory neuropathy type Ia (HMSN type Ia) is an autosomal dominant demyelinating polyneuropathy, which may result from duplications as large as 1.5 Mb on chromosome 17p 11.2-p12 encompassing the gene for the peripheral myelin protein PMP22, or from point mutations in this gene. In general, it is not possible to distinguish, by clinical and neurophysiological criteria, the cases associated with the duplication mutation from those associated with point mutations of the PMP22 gene, although the latter tend to be more severe. In this study we demonstrated that the two genotypes exhibit different morphological characteristics. In the PMP22 duplicated cases the mean g-ratio (axon diameter versus fibre diameter) is significantly lower than normal, while in cases of PMP22 point mutations nearly all myelinated fibers have an extremely high g-ratio. In cases with point mutations, onion bulbs are abundantly present from an early age, whereas onion bulbs in the duplicated cases develop gradually in the first years of life. Increase in total transverse fascicular area is most pronounced in the point mutation cases. The differences in pathology between these two very different types of mutations involving the same gene likely reflect differences in pathogenesis and may offer clues in understanding the function of PMP22.

    Acta neuropathologica 1995;90;6;645-9

  • A G to T mutation at a splice site in a case of Pelizaeus-Merzbacher disease.

    Strautnieks S and Malcolm S

    Molecular Genetics Unit, Institute of Child Health, London, UK.

    Human molecular genetics 1993;2;12;2191-2

  • A novel insertional mutation at exon VII of the myelin proteolipid protein gene in Pelizaeus-Merzbacher disease.

    Kurosawa K, Iwaki A, Miyake S, Imaizumi K, Kuroki Y and Fukumaki Y

    Institute of Genetic Information, Kyushu University, Fukuoka, Japan.

    Pelizaeus-Merzbacher disease (PMD) is an X-linked neurological disorder characterized by dysmyelination in the central nervous system (CNS). Recently mutations of the myelin proteolipid protein (PLP) gene which encodes both PLP and its isoform, DM-20 generated by alternative splicing, have been demonstrated in PMD patients. We analyzed the seven exons of the PLP gene of a Japanese boy affected with PMD by direct sequencing and identified an insertion event in exon VII of the PLP gene. This mutation was also present in his carrier mother, but was absent in ninety-five X chromosomes of normal Japanese. The frame-shift mutation leads to the production of truncated PLP with altered carboxyl terminal amino acid sequences, resulting in considerable change of the structure of PLP and DM-20 necessary for functional purposes. This is the first report of a mutation in exon VII of the PLP gene associated with PMD.

    Human molecular genetics 1993;2;12;2187-9

  • Identification of a new polymorphism in the human proteolipid protein gene.

    Poduslo SE, Decker P, Astle H, Kurth J and LaBate M

    Department of Neurology, Texas Tech University Health Sciences Center, Lubbock 79430.

    A polymorphism in the gene for proteolipid protein has been identified, using amplification by the polymerase chain reaction, restriction enzyme digestion, and fragment separation by polyacrylamide gel electrophoresis. The polymorphism is located in the transcribed 3'-untranslated region, a region with potential regulatory signals. The mutation consists of a single base pair insertion into a Hae III restriction site, producing a larger rare fragment of 409 bp as compared with the more frequent 325 bp fragment. The gene for proteolipid protein is on the X chromosome; thus the males are hemizygous for the rare allele and the females are heterozygous carriers. The polymorphism occurs with a frequency of 0.046 in a population of European origin and also has a rare frequency in multiple sclerosis patients.

    Neurochemistry international 1993;23;5;413-7

  • Linkage of a new mutation in the proteolipid protein (PLP) gene to Pelizaeus-Merzbacher disease (PMD) in a large Finnish kindred.

    Pratt VM, Kiefer JR, Lähdetie J, Schleutker J, Hodes ME and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251.

    The purpose of this study was to confirm linkage of the proteolipid protein gene (PLP) and Pelizaeus-Merzbacher disease (PMD). A T-->A transversion in nucleotide pair 35 of exon 4 of PLP was found in a large Finnish kindred with PMD. This mutation results in the substitution Val165-->Glu165. We used a combination of single-strand conformational polymorphism and PCR primer extension to determine the presence or absence of the point mutation in family members. A lod score of 2.6 (theta = 0) was found for linkage of the gene and the disease. We examined 101 unrelated X chromosomes and found none with the transversion. This is the second report of linkage of PMD to a missense mutation in PLP. These findings support the hypothesis that PMD in this family is a result of the missense mutation present in exon 4 of PLP.

    American journal of human genetics 1993;52;6;1053-6

  • Pelizaeus-Merzbacher disease: a frameshift deletion/insertion event in the myelin proteolipid gene.

    Pham-Dinh D, Boespflug-Tanguy O, Mimault C, Cavagna A, Giraud G, Leberre G, Lemarec B and Dautigny A

    Equipe ATIPE, URA 1488 CNRS, Paris, France.

    Among the central nervous system (CNS) dysmyelinating disorders, Pelizaeus-Merzbacher disease (PMD) has been individualized by its X-linked mode of inheritance and the existence of corresponding animal models. Mutations in the major myelin proteolipid (PLP) gene coding for PLP and its splicing variant DM20 protein, have been demonstrated in animal mutants and more recently in PMD affected patients. We have identified, in a two-generation PMD affected family, an insertion/deletion event in the exon IV of the PLP gene, leading to the synthesis of predicted truncated PLP and DM20 proteins with altered carboxyl terminal end. This is the first report of a frameshift mutation in the PLP gene in PMD.

    Human molecular genetics 1993;2;4;465-7

  • A novel mutation in the proteolipid protein gene leading to Pelizaeus-Merzbacher disease.

    Otterbach B, Stoffel W and Ramaekers V

    Institut für Biochemie, Medizinische Fakultät, Universität Köln.

    Point mutations of the gene of human proteolipid protein (PLP) have been recognized as the molecular basis of one form of leukodystrophy, the X-chromosome-linked Pelizaeus-Merzbacher disease (PMD). We report the molecular analysis of four PMD patients in three unrelated families and describe a point mutation (G-->A transition) in exon V which leads to the substitution of Gly216 by a serine residue in a highly conserved extracytosolic domain and a Mae I RFLP. Molecular modelling with energy minimization indicates that this seemingly minor alteration of the amino-acid sequence induces a considerable conformational change and tight packing of the polypeptide chain apparently not compatible with the regular PLP function in oligodendrocytes. This mutation has been detected and characterized by PCR amplification of genomic DNA using intron and exon primers and the complete sequence analysis of the seven exons and a 300 bp promoter region of the PLP gene of two affected brothers. The sequence analysis of a PCR fragment representing exon V amplified from genomic DNA of different kindreds of the pedigree revealed the mother as the only carrier indicating that the mutation has occurred de novo in the mother's germline. PLP gene (including the 8.8 kb intron I) rearrangements have been excluded by Southern blot hybridization and overlapping PCR amplification of genomic DNA.

    Biological chemistry Hoppe-Seyler 1993;374;1;75-83

  • Molecular diagnostics for myelin proteolipid protein gene mutations in Pelizaeus-Merzbacher disease.

    Doll R, Natowicz MR, Schiffmann R and Smith FI

    Division of Biochemistry and Molecular Biology, Eunice K. Shriver Center for Mental Retardation, Waltham, MA 02254.

    Pelizaeus-Merzbacher disease (PMD) is a clinically heterogeneous, slowly progressive leukodystrophy. The recent detection of mutations in the myelin proteolipid protein (PLP) gene in several PMD patients offers the opportunity both to design DNA-based tests that would be useful in diagnosing a proportion of PMD cases and, in particular, to evaluate the diagnostic utility of single-strand conformation polymorphism (SSCP) analysis for this disease. A combination of SSCP analysis and direct sequencing of PCR-amplified DNA was used to screen for PLP mutations in 24 patients affected with leukodystrophies of unknown etiology. Two heretofore undescribed mutations in the PLP gene were identified, Asp202His in exon 4 and Gly73Arg in exon 3. The ease and efficiency of SSCP analysis in detecting new mutations support the utilization of this technique in screening for PLP mutations in patients with unexplained leukodystrophies.

    Funded by: NIDDK NIH HHS: DK38381

    American journal of human genetics 1992;51;1;161-9

  • New variant in exon 3 of the proteolipid protein (PLP) gene in a family with Pelizaeus-Merzbacher disease.

    Pratt VM, Trofatter JA, Larsen MB, Hodes ME and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School Medicine Indianapolis 46202-5251.

    A C--greater than G transversion has been found in exon 3 of the PLP gene of affected males and their mother in a single sibship with Pelizaeus-merzbacher disease (PMD). The transversion should not result in an amino acid change in the protein but it does result in the loss of a HaeIII restriction endonuclease cleavage site. It is concordant with the disease in this family. One-hundred-ten unrelated X chromosomes are negative for this mutation. No other sequence defect was found in the PLP exons of the affected males. The cause of disease in this family remains unknown, but the association between this rare mutation and PMD is intriguing. The mutation can serve as a marker for following segregation of the PLP gene.

    American journal of medical genetics 1992;43;3;642-6

  • Complete deletion of the proteolipid protein gene (PLP) in a family with X-linked Pelizaeus-Merzbacher disease.

    Raskind WH, Williams CA, Hudson LD and Bird TD

    Department of Medicine, University of Washington School of Medicine, Seattle 98195.

    Pelizaeus-Merzbacher disease (PMD) is an X-linked neurologic disorder characterized by dysmyelination in the central nervous system. Proteolipid protein (PLP), a major structural protein of myelin, is coded on the X chromosome. It has been postulated that a defect in the PLP gene is responsible for PMD. Different single-nucleotide substitutions have been found in conserved regions of the PLP gene of four unrelated PMD patients. Novel Southern blot patterns suggested a complex rearrangement in a fifth family. Linkage to PLP has been shown in others. We evaluated the PLP locus in a four-generation family with two living males affected with X-linked PMD. Analysis of DNA from the affected males revealed complete absence of a band, with PLP probes encompassing the promoter region, the entire coding region, and the 3' untranslated region and spanning at least 29 kb of genomic DNA. DNA from unaffected relatives gave the expected band pattern. Two obligate and one probable carrier women were hemizygous for the PLP locus by dosage analysis. Although it is unlikely, the previously described point mutations in PLP could represent polymorphisms. The finding of complete deletion of the PLP gene in our family is a stronger argument that mutations in PLP are responsible for X-linked PMD.

    Funded by: NCI NIH HHS: CA 16448

    American journal of human genetics 1991;49;6;1355-60

  • Pelizaeus-Merzbacher disease: tight linkage to proteolipid protein gene exon variant.

    Trofatter JA, Dlouhy SR, DeMyer W, Conneally PM and Hodes ME

    Department of Medical Genetics, Indiana University Medical Center, Indianapolis 46223.

    Pelizaeus-Merzbacher disease (PMD) is a human X chromosome-linked dysmyelination disorder of the central nervous system for which the genetic defect has not yet been established. The jimpy mutation jp of the mouse is an X chromosome-linked disorder of myelin formation. The mutation is at an intron/exon splice site in the mouse gene for proteolipid protein (PLP). With the jimpy mouse mutation as a precedent, we focused our attention on the human PLP gene, which is found at Xq22. The polymerase chain reaction was used to amplify the exons of the PLP gene of an affected male from a large Indiana PMD kindred. DNA sequencing showed a C----T transition at nucleotide 40 of the second exon. An affected third cousin also showed this sequence variation, while two unaffected male relatives (sons of an obligate carrier female) had the normal cytidine nucleotide. Allele-specific oligonucleotides were used to generate data for linkage studies on the above mentioned PMD kindred. Our results show tight linkage (theta = 0) of PMD to PLP with a lod (logarithm of odds) score of 4.62. In six other unrelated PMD kindreds, only the normal-sequence oligonucleotide hybridized, which indicates genetic heterogeneity. The radical nature of the predicted amino acid change (proline to leucine), suggests that the PMD-causing defect may have been delineated in one kindred.

    Proceedings of the National Academy of Sciences of the United States of America 1989;86;23;9427-30

Literature (120)

Pubmed - human_disease

  • PLP1 and GPM6B intragenic copy number analysis by MAPH in 262 patients with hypomyelinating leukodystrophies: Identification of one partial triplication and two partial deletions of PLP1.

    Combes P, Bonnet-Dupeyron MN, Gauthier-Barichard F, Schiffmann R, Bertini E, Rodriguez D, Armour JA, Boespflug-Tanguy O and Vaurs-Barrière C

    INSERM U 384, Faculté de Médecine, Place Henri Dunant, 63000 Clermont-Ferrand, France.

    The proteolipid protein 1 (PLP1) gene is known to be mutated in the X-linked disorders of myelin formation Pelizaeus-Merzbacher disease (PMD) and spastic paraplegia type 2. The most commonly found PLP1 mutations are gene duplications (60-70%) and point mutations (20%). About 20% of patients with a PMD phenotype do not present identified PLP1 mutation, thus suggesting genetic heterogeneity and/or undetected PLP1 abnormalities. Except the recently described MLPA screening the seven exonic regions, the currently used techniques to quantify PLP1 gene copy number do not investigate small intragenic PLP1 rearrangements. Using the multiplex amplifiable probe hybridization (MAPH) technique, we looked simultaneously for intragenic rearrangements along the PLP1 gene (exonic and regulatory regions) and for rearrangements in the GPM6B candidate gene (a member of the proteolipid protein family). We tested 262 hypomyelinating patients: 56 PLP1 duplicated patients, 1 PLP1 triplicated patient, and 205 patients presenting a leukodystrophy of undetermined origin with brain MRI suggesting a defect in myelin formation. Our results show that MAPH is an alternative reliable technique for diagnosis of PLP1 gene copy number. It allows us (1) to demonstrate that all PLP1 duplications previously found encompass the whole gene, (2) to establish that copy number changes in GPM6B and intragenic duplications of PLP1 are very unlikely to be involved in the etiology of UHL, and (3) to identify one partial triplication and two partial deletions of PLP1 in patients presenting with a PMD phenotype.

    Neurogenetics 2006;7;1;31-7

  • Three or more copies of the proteolipid protein gene PLP1 cause severe Pelizaeus-Merzbacher disease.

    Wolf NI, Sistermans EA, Cundall M, Hobson GM, Davis-Williams AP, Palmer R, Stubbs P, Davies S, Endziniene M, Wu Y, Chong WK, Malcolm S, Surtees R, Garbern JY and Woodward KJ

    Clinical and Molecular Genetics, Institute of Child Health, London, UK.

    We describe five boys from different families with an atypically severe form of Pelizaeus-Merzbacher disease (PMD) who have three, and in one case, five copies of the proteolipid protein (PLP1) gene. This is the first report of more than two copies of PLP1 in PMD patients and clearly demonstrates that severe clinical symptoms are associated with increased PLP1 gene dosage. Previously, duplications, deletions and mutations of the PLP1 gene were reported to give rise to this X-linked disorder. Patients with PLP1 duplication are usually classified as having either classical or transitional PMD rather than the more rare severe connatal form. The clinical symptoms of the five patients in this study included lack of stable head control and severe mental retardation, with three having severe paroxysmal disorder and two dying before the first year of life. Gene dosage was determined using interphase FISH (fluorescence in situ hybridization) and the novel approach of multiple ligation probe amplification (MLPA). We found FISH unreliable for dosage detection above the level of a duplication and MLPA to be more accurate in determination of specific copy number. Our finding that three or more copies of the gene give rise to a more severe phenotype is in agreement with observations in transgenic mice where severity of disease increased with Plp1 gene dosage and level of overexpression. The patient with five copies of PLP1 was not more affected than those with a triplication, suggesting that there is possibly a limit to the level of severity or that other genetic factors influence the phenotype. It highlights the significance of PLP1 dosage in CNS myelinogenesis as well as the importance of accurate determination of PLP1 gene copy number in the diagnosis of PMD and carrier detection.

    Brain : a journal of neurology 2005;128;Pt 4;743-51

  • [Duplication of the PLP gene and the classical form of Pelizaeus-Merzbacher disease].

    Blanco-Barca MO, Eirís-Puñal J, Soler-Regal C and Castro-Gago M

    Servicio de Neuropediatría, Departamento de Pediatría, Hospital Clínico Universitario, Santiago de Compostela, España.

    Introduction: Pelizaeus-Merzbacher disease (PMD) is a rare form of sudanophilic leukodystrophy which is transmitted by recessive inheritance linked to the X chromosome. It only affects the myelin of the central nervous system (CNS) and is caused by a proteolipid protein (PLP) deficit, which is coded for in Xq21.2-q22. Presentation follows a classical or connatal pattern and is associated with nystagmus, stridor and pyramidal/extrapyramidal manifestations within the framework of a clinical picture of psychomotor retardation and regression with variable clinical course and presentation.

    A 37-month-old male, with sever psychomotor retardation, nystagmus and choreoathetotic movements with a stationary developmental profile. An MRI scan of the brain showed severe supratentorial hypomyelination and peripheral electrophysiological explorations (EMG and NCS) were normal. The genetic study using PCR revealed duplication in the PLP gene.

    Conclusion: This observation corresponds to a classical form of PMD, which must be taken into account when associated with: 1) Psychomotor retardation; 2) Early nystagmus; 3) Pyramidal/extrapyramidal involvement; 4) Absence of peripheral neurophysiological involvement; 5) A neuroradiological pattern of hypomyelination of the CNS.

    Revista de neurologia 2003;37;5;436-8

  • Myelination of a fetus with Pelizaeus-Merzbacher disease: immunopathological study.

    Shiraishi K, Itoh M, Sano K, Takashima S and Kubota T

    Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan.

    We report an autopsied case of a 21-gestational-week fetus with duplication of the proteolipid protein (PLP) gene (PLP1). An immunohistochemical study, which can detect the specific expression of PLP, myelin basic protein, myelin-associated glycoprotein, and platelet-derived growth factor receptor alpha subunit in brain tissues, showed that the myelination was almost the same as that of age-matched controls. This result suggests that the development and migration of the oligodendrocyte is normal in Pelizaeus-Merzbacher disease until midgestation. To our knowledge, this is the first report of the myelination of a fetus with duplication of the PLP1 gene.

    Annals of neurology 2003;54;2;259-62

  • Complex chromosomal rearrangement and associated counseling issues in a family with Pelizaeus-Merzbacher disease.

    Woodward K, Cundall M, Palmer R, Surtees R, Winter RM and Malcolm S

    Clinical and Molecular Genetics Unit, Institute of Child Health, London, United Kingdom. k.woodward@ich.ucl.ac.uk

    We report cytogenetic and molecular findings in a family in which Pelizaeus-Merzbacher disease has arisen by a sub-microscopic duplication of the proteolipid protein (PLP1) gene involving the insertion of approximately 600 kb from Xq22 into Xq26.3. The duplication arose in an asymptomatic mother on a paternally derived X chromosome and was inherited by her son, the proband, who is affected with Pelizaeus-Merzbacher disease. The mother also carries a large interstitial deletion of approximately 70 Mb extending from Xq21.1 to Xq27.3, which is present in a mosaic form. In lymphocytes, the mother has no normal cells, having one population with three copies of the PLP1gene (one normal X and one duplication X chromosome) and the other population having only one copy of the PLP1 gene (one normal X and one deleted X chromosome). Her karyotype is 46,XX.ish dup (X) (Xpter --> Xq26.3::Xq22 --> Xq22::Xq26.3 --> Xqter)(PLP++)/46,X,del(X)(q21.1q27.3).ish del(X)(q21.1q27.3)(PLP-). Both ends of the deletion have been mapped by fluorescence in situ hybridization using selected DNA clones and neither involves the PLP1 gene or are in the vicinity of the duplication breakpoints. Prenatal diagnosis was carried out in a recent pregnancy and the complex counseling issues associated with these chromosomal rearrangements are discussed.

    American journal of medical genetics. Part A 2003;118A;1;15-24

  • A severe connatal form of Pelizaeus Merzbacher disease in a Czech boy caused by a novel mutation (725C>A, Ala242Glu) at the 'jimpy(msd) codon' in the PLP gene.

    Seeman P, Paderova K, Benes V and Sistermans EA

    Department of Child Neurology, Second School of Medicine, Charles University and University Hospital Motol, Prague, 150 06 Prague 5, Czech Republic. pavel.seeman@lfmotol.cuni.cz

    Pelizaeus Merzbacher disease (PMD) is an X-linked recessive disorder of the central nervous system myelination caused by mutations involving the proteolipid protein gene (PLP). Early nystagmus and developmental delay, progressive pyramidal, cerebellar and dystonic signs as well as white matter changes in brain MRI are typical for PMD. The PLP gene can be affected by two major types of mutations. A duplication of the whole PLP gene is the most common mutation and results usually in the milder classical phenotype, whereas point mutations in PLP gene often result in the rarer and more severe connatal form of PMD. The PLP protein is a higly conserved across species and is identical in human, mouse and rat. We describe a 13-year-old Czech boy with an early and severe developmental delay. His maternal uncle died at the age of one year and was also early and severely psychomotoricly retarded. The patient was the first child of healthy unrelated parents born after an uneventful pregnancy and delivery in 1988. Hyperbilirubinemia and bronchopneumonia and early stridor complicated his neonatal period. Diffuse hypotonia, nystagmus, psychomotor retardation, visual and hearing impairment have been observed in the patient since the age of 6 weeks. White matter abnormalities, cortical and periventricular atrophy were detected by MRI at the age of 6 and 11 years, respectively. Despite these signs and results an accurate clinical diagnosis was unclear until the age of 11 years. Last neurological examination in 1999 showed no nystagmus anymore, but extremely dystrophic limbs, truncal deformation, due to severe scoliosis, tetraplegia with hyperreflexia in C5C7 and areflexia L2S2 and positive pyramidal signs. The boy had no visual or speech contact. DNA tests followed the clinical suspicion for PMD. At first, duplication of PLP gene was excluded by quantitative comparative PCR. Direct sequencing of PLP gene detected a novel mutation in exon 6, a missense mutation 725C-->A (Ala242Glu) in the patient and in his mother and later also in his maternal grandmother. The same codon, but to valine (Ala242Val) is mutated in jimpy(msd) mouse, which is the frequently used animal model for PMD. Prenatal diagnosis for the next pregnancy has been offered to the family. The patient died recently at the age of 13 years due to respiratory failure. Our results support the data on the importance of this conserved amino acid alanine at codon 242.

    International journal of molecular medicine 2002;9;2;125-9

  • Prenatal interphase FISH diagnosis of PLP1 duplication associated with Pelizaeus-Merzbacher disease.

    Inoue K, Kanai M, Tanabe Y, Kubota T, Kashork CD, Wakui K, Fukushima Y, Lupski JR and Shaffer LG

    Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.

    A submicroscopic genomic duplication in Xq22.2 that contains the entire proteolipid protein 1 gene (PLP1) is responsible for the majority of Pelizaeus-Merzbacher disease (PMD) patients. We previously developed an interphase FISH assay to screen for PLP1 duplications in PMD patients using peripheral blood and lymphoblastoid cell lines. This assay has been utilized as a clinical diagnostic test in our cytogenetics laboratory. To expand usage of the interphase FISH assay to prenatal diagnosis of PLP1 duplications, we examined three PMD families with PLP1 duplications utilizing aminiotic fluid samples. In two families the FISH assay revealed fetuses with PLP1 duplications, whereas the other fetus showed a normal copy number of PLP1. Haplotype analyses, as well as an additional FISH analysis using postnatal blood samples, confirmed the results of the prenatal analyses. Our study demonstrates utility of the interphase FISH assay in the prenatal diagnosis of PLP1 duplications in PMD.

    Funded by: NICHD NIH HHS: P30 HD24064; NINDS NIH HHS: R01 NS27042

    Prenatal diagnosis 2001;21;13;1133-6

  • Prenatal diagnosis of Pelizaeus-Merzbacher disease: detection of proteolipid protein gene duplication by quantitative fluorescent multiplex PCR.

    Regis S, Filocamo M, Mazzotti R, Cusano R, Corsolini F, Bonuccelli G, Stroppiano M and Gatti R

    Laboratorio di Diagnosi Pre e Postnatale di Malattie Metaboliche, Istituto G. Gaslini, Largo G. Gaslini 5, 16147 Genoa, Italy. dppm@ospedale-gaslini.ge.it

    A prenatal diagnosis of Pelizaeus-Merzbacher disease (PMD) resulting from proteolipid protein gene (PLP) duplication was performed by a quantitative fluorescent multiplex PCR method. PLP gene copy number was determined in the proband, the pregnant mother, the male fetus and two aunts. Small amounts of genomic DNA extracted from peripheral blood and from chorionic villi were used. The fetus, in common with the proband, was identified as PMD-affected being a carrier of the PLP gene duplication, inherited from the mother, while the two aunts were non-carriers. The data obtained were confirmed by segregation analysis of a PLP-associated dinucleotide-repeat polymorphism amplified by the same multiplex PCR.

    Prenatal diagnosis 2001;21;8;668-71

  • A new polymorphism in the proteolipid protein (PLP1) gene and its use for carrier detection of PLP1 gene duplication in Pelizaeus-Merzbacher disease.

    Hobson G, Stabley D, Funanage V and Marks H

    Department of Research, Alfred I. DuPont Hospital for Children, Wilmington, DE, USA. ghobson@nemours.org

    Pelizaeus Merzbacher Disease (PMD) is an X-linked recessive dysmyelinating disorder of the central nervous system. Most patients have point mutations in exons of the proteolipid protein (PLP1) gene or duplication of a genomic region that includes the PLP1 gene. We identified a common MspI polymorphism in intron 1 of the PLP1 gene and used it to determine carrier status for PLP1 gene duplication in PMD by using a quantitative PCR approach.

    Human mutation 2001;17;2;152

  • A novel deletion (c663delC) at exon 5 of the proteolipid protein gene in Pelizaeus-Merzbacher disease.

    Matsumura T, Osaka H, Inoue K, Sugiyama N, Onishi H, Yamada Y, Hayashi M and Kosaka K

    Department of Psychiatry, School of Medicine, Yokohama City University, Tokyo, Japan.

    Human mutation 2001;17;1;80

  • Mutations in noncoding regions of the proteolipid protein gene in Pelizaeus-Merzbacher disease.

    Hobson GM, Davis AP, Stowell NC, Kolodny EH, Sistermans EA, de Coo IF, Funanage VL and Marks HG

    Department of Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19899, USA. ghobson@nemours.org

    Background: Pelizaeus-Merzbacher disease (PMD) is an X-linked recessive dysmyelinating disorder of the CNS. Duplications or point mutations in exons of the proteolipid protein (PLP) gene are found in most patients.

    Objective: To describe five patients with PMD who have mutations in noncoding regions of the PLP gene.

    Methods: Quantitative multiplex PCR and Southern blot analyses were used to detect duplication of the PLP gene, and DNA sequence analysis, including exon-intron borders, was used to detect mutation of the PLP gene.

    Results: Duplication of the PLP gene was ruled out, and mutations were identified in noncoding regions of five patients in four families with PMD. In two brothers with a severe form of PMD, a G to T transversion at IVS6+3 was detected. This mutation resulted in skipping of exon 6 in the PLP mRNA of cultured fibroblasts. A patient who developed nystagmus at 16 months and progressive spastic ataxia at 18 months was found to have a 19-base pair (bp) deletion of a G-rich region near the 5' end of intron 3 of the PLP gene. A patient with a T to C transition at IVS3+2 and a patient with an A to G transition at IVS3+4 have the classic form of PMD. These, like the 19-bp deletion, are in intron 3, which is involved in PLP/DM20 alternative splice site selection.

    Conclusions: Mutations in introns of the PLP gene, even at positions that are not 100% conserved at splice sites, are an important cause of PMD.

    Neurology 2000;55;8;1089-96

  • Additional copies of the proteolipid protein gene causing Pelizaeus-Merzbacher disease arise by separate integration into the X chromosome.

    Hodes ME, Woodward K, Spinner NB, Emanuel BS, Enrico-Simon A, Kamholz J, Stambolian D, Zackai EH, Pratt VM, Thomas IT, Crandall K, Dlouhy SR and Malcolm S

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202, USA. mhodes@iupui.edu

    The proteolipid protein gene (PLP) is normally present at chromosome Xq22. Mutations and duplications of this gene are associated with Pelizaeus-Merzbacher disease (PMD). Here we describe two new families in which males affected with PMD were found to have a copy of PLP on the short arm of the X chromosome, in addition to a normal copy on Xq22. In the first family, the extra copy was first detected by the presence of heterozygosity of the AhaII dimorphism within the PLP gene. The results of FISH analysis showed an additional copy of PLP in Xp22.1, although no chromosomal rearrangements could be detected by standard karyotype analysis. Another three affected males from the family had similar findings. In a second unrelated family with signs of PMD, cytogenetic analysis showed a pericentric inversion of the X chromosome. In the inv(X) carried by several affected family members, FISH showed PLP signals at Xp11.4 and Xq22. A third family has previously been reported, in which affected members had an extra copy of the PLP gene detected at Xq26 in a chromosome with an otherwise normal banding pattern. The identification of three separate families in which PLP is duplicated at a noncontiguous site suggests that such duplications could be a relatively common but previously undetected cause of genetic disorders.

    Funded by: NICHD NIH HHS: HD26979, P30 HD026979

    American journal of human genetics 2000;67;1;14-22

  • MR-revealed myelination in the cerebral corticospinal tract as a marker for Pelizaeus-Merzbacher's disease with proteolipid protein gene duplication.

    Takanashi J, Sugita K, Tanabe Y, Nagasawa K, Inoue K, Osaka H and Kohno Y

    Department of Pediatrics, Faculty of Medicine, Chiba University, Chiba-shi, Japan.

    Pelizaeus-Merzbacher's disease (PMD) is caused by mutations in the proteolipid protein (PLP) gene. Recent studies have shown that an increased PLP dosage, resulting from total duplication of the PLP gene, invariably causes the classic form of PMD. The purpose of this study was to compare the MR findings of PMD attributable to PLP duplication with those of PMD arising from a missense mutation.

    Methods: Seven patients with PMD, three with a PLP missense mutation in either exon 2 or 5 (patients 1-3), and four with PLP duplication (patient 4 having larger PLP duplication than patients 5-7) were clinically classified as having either the classic or connatal form of PMD. Cerebral MR images were obtained to analyze the presence of myelination and T1 and T2 shortening in the deep gray matter. Multiple MR studies were performed in six of the seven patients to analyze longitudinal changes.

    Results: Four patients (patients 1-4) were classified as having connatal PMD, whereas the other three (patients 5-7) were classified as having classic PMD. Myelination in the cerebral corticospinal tract, optic radiation, and corpus callosum was observed in three cases of classic PMD with PLP duplication. In patient 4, myelination extended to the internal capsule, corona radiata, and centrum semiovale over a 3-year period. No myelination was observed in three PMD cases with a PLP point mutation. T2 shortening in the deep gray matter was recognized in all patients with PMD.

    Conclusion: The presence of myelination in the cerebral corticospinal tract with diffuse white matter hypomyelination on MR images could be a marker for PMD with PLP duplication. It is suggested that progression of myelination may be present in connatal PMD with large PLP duplication.

    AJNR. American journal of neuroradiology 1999;20;10;1822-8

  • A novel mutation (A246T) in exon 6 of the proteolipid protein gene associated with connatal Pelizaeus-Merzbacher disease.

    Yamamoto T and Nanba E

    Gene Research Center, Tottori University, Yonago 683-8503, Japan.

    Human mutation 1999;14;2;182

  • A de novo splice donor site mutation causes in-frame deletion of 14 amino acids in the proteolipid protein in Pelizaeus-Merzbacher disease.

    Aoyagi Y, Kobayashi H, Tanaka K, Ozawa T, Nitta H and Tsuji S

    Department of Neurology, Brain Research Institute, Niigata University, Japan.

    Pelizaeus-Merzbacher disease (PMD) is a leukodystrophy associated with mutations in the proteolipid protein (PLP) gene. Jimpy is a mouse model of human PMD, and a splice site mutation in Jimpy causes the deletion of exon 5 from the PLP mRNA, producing a truncated form of PLP. We describe a de novo point mutation at the 5' splice donor site of exon 5 in a 17-year-old male with PMD, which results in the skipping of 42 base pairs of exon 5. The mutation removes only 14 amino acids in-frame of PLP. This is a novel splice donor site mutation in the human PLP gene. Moreover, the results indicate that the 14-amino acid deletion in the PLP is responsible for oligodendrocyte cell death and the development of PMD.

    Annals of neurology 1999;46;1;112-5

  • Family with Pelizaeus-Merzbacher disease/X-linked spastic paraplegia and a nonsense mutation in exon 6 of the proteolipid protein gene.

    Bond C, Si X, Crisp M, Wong P, Paulson GW, Boesel CP, Dlouhy SR and Hodes ME

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA.

    We report on a C-to-T transition in exon 6 of the PLP gene in a male with Pelizaeus-Merzbacher disease/X-linked spastic paraplegia. The transition changes a glutamine at amino acid residue 233 to a termination codon. This premature stop codon probably results in a truncated protein that is not functional. Six other relatives were analyzed for the mutation and two female carriers were identified. Autopsy data on one male are presented.

    Funded by: NICHD NIH HHS: 2T32HD07373

    American journal of medical genetics 1997;71;3;357-60

  • A new proteolipid lipoprotein mutation in Pelizaeus-Merzbacher disease.

    Verhagen WI, Huygen PL, Smeets HJ, Renier WO and de Wijs I

    Journal of the neurological sciences 1997;147;2;215-6

  • Nonsense mutation in exon 3 of the proteolipid protein gene (PLP) in a family with an unusual form of Pelizaeus-Merzbacher disease.

    Hodes ME, Blank CA, Pratt VM, Morales J, Napier J and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA.

    We report a G-->A transition at nucleotide 431 of the proteolipid protein gene (PLP) results in a nonsense codon in a family with an unusual form of Pelizaeus-Merzbacher disease (PMD). The mutation, which creates a second AluI restriction site, results in a nonsense mutation in PLP. The clinical picture resembles somewhat that of X-linked spastic paraplegia (SPG). It differs from this and both the classical and connatal forms of PMD in that it is relatively mild in form, onset is delayed beyond age 2 years, nystagmus is absent, tremors are prominent, mental retardation is not severe, some patients show dementia or personality disorders, the disease is progressive rather than static in some, and several females show signs of disease. The nonsense mutation, which is in exon 3B, should block the synthesis of normal PLP but spare DM20, the isoform whose persistence has been associated with mild forms of PLP-associated disease in both humans and mice.

    American journal of medical genetics 1997;69;2;121-5

  • A (G-to-A) mutation in the initiation codon of the proteolipid protein gene causing a relatively mild form of Pelizaeus-Merzbacher disease in a Dutch family.

    Sistermans EA, de Wijs IJ, de Coo RF, Smit LM, Menko FH and van Oost BA

    Department of Human Genetics, University Hospital Nijmegen, The Netherlands.

    Pelizaeus-Merzbacher disease (PMD) is an X-linked recessive disorder that is characterized by dysmyelination of the central nervous system resulting from mutations in the proteolipid protein (PLP) gene. Mutations causing either overexpression or expression of a truncated form of PLP result in oligodendrocyte cell death because of accumulation of PLP in the endoplasmic reticulum. It has therefore been hypothesized that absence of the protein should result in a less severe phenotype. However, until now, only one patient has been described with a complete deletion of the PLP gene. We report a Dutch family with a relatively mild form of PMD, in which the disease cosegregates with a (G-to-A) mutation in the initiation codon of the PLP gene. This mutation should cause the total absence of PLP and is therefore in agreement with the hypothesis that absence of PLP leads to a mild form of PMD.

    Human genetics 1996;97;3;337-9

  • Girl with signs of Pelizaeus-Merzbacher disease heterozygous for a mutation in exon 2 of the proteolipid protein gene.

    Hodes ME, DeMyer WE, Pratt VM, Edwards MK and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA.

    We studied a female infant with clinical signs of Pelizaeus-Merzbacher disease (PMD), who has a familial mutation (C41-->T) in exon 2 of the proteolipid protein gene (PLP), and selected relatives. While the carrier mother and grandmother of the proposita currently are neurologically normal and show normal T2 magnetic resonance imaging (MRI) of the brain, the infant has a neurological picture, MRIs, and brain auditory evoked response (BAER) consistent with that diagnosis. The data here presented show that PMD can occur in females carrying a mutation in the PLP gene. Our experience with the MRIs of this patient, her mother and grandmother, and those of a previously reported family [Pratt et al.: Am J Med Genet 38:136-139, 1991] show that molecular genetic analysis and not MRI is the appropriate means for carrier detection.

    American journal of medical genetics 1995;55;4;397-401

  • Pelizaeus-Merzbacher disease in a family of Portuguese origin caused by a point mutation in exon 5 of the proteolipid protein gene.

    Pratt VM, Boyadjiev S, Dlouhy SR, Silver K, Der Kaloustian VM and Hodes ME

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA.

    Single-strand conformational polymorphism analysis of an affected male with Pelizaeus-Merzbacher disease (PMD) showed a slight change in mobility of amplified exon 5 of the proteolipid protein (PLP) gene. The exon was sequenced and a G-->A transition at codon 216 was found. This mutation eliminates a BstNI restriction site and creates a MaeI restriction site. In 1989, Gencic et al. reported a mutation that destroyed the same BstNI site, but resulted in a substitution at codon 215 [Am J Hum Genet 45:435-442]. The mutation we report here is also present in the patient's mother and her male fetus as determined by polymerase chain reaction analysis of amniocytes.

    American journal of medical genetics 1995;55;4;402-4

  • Charcot-Marie-Tooth disease type 1A: morphological phenotype of the 17p duplication versus PMP22 point mutations.

    Gabreëls-Festen AA, Bolhuis PA, Hoogendijk JE, Valentijn LJ, Eshuis EJ and Gabreëls FJ

    Institute of Neurology, University Hospital Nijmegen, The Netherlands.

    Charcot-Marie-Tooth disease type 1A (CMT1A) or hereditary motor and sensory neuropathy type Ia (HMSN type Ia) is an autosomal dominant demyelinating polyneuropathy, which may result from duplications as large as 1.5 Mb on chromosome 17p 11.2-p12 encompassing the gene for the peripheral myelin protein PMP22, or from point mutations in this gene. In general, it is not possible to distinguish, by clinical and neurophysiological criteria, the cases associated with the duplication mutation from those associated with point mutations of the PMP22 gene, although the latter tend to be more severe. In this study we demonstrated that the two genotypes exhibit different morphological characteristics. In the PMP22 duplicated cases the mean g-ratio (axon diameter versus fibre diameter) is significantly lower than normal, while in cases of PMP22 point mutations nearly all myelinated fibers have an extremely high g-ratio. In cases with point mutations, onion bulbs are abundantly present from an early age, whereas onion bulbs in the duplicated cases develop gradually in the first years of life. Increase in total transverse fascicular area is most pronounced in the point mutation cases. The differences in pathology between these two very different types of mutations involving the same gene likely reflect differences in pathogenesis and may offer clues in understanding the function of PMP22.

    Acta neuropathologica 1995;90;6;645-9

  • A G to T mutation at a splice site in a case of Pelizaeus-Merzbacher disease.

    Strautnieks S and Malcolm S

    Molecular Genetics Unit, Institute of Child Health, London, UK.

    Human molecular genetics 1993;2;12;2191-2

  • A novel insertional mutation at exon VII of the myelin proteolipid protein gene in Pelizaeus-Merzbacher disease.

    Kurosawa K, Iwaki A, Miyake S, Imaizumi K, Kuroki Y and Fukumaki Y

    Institute of Genetic Information, Kyushu University, Fukuoka, Japan.

    Pelizaeus-Merzbacher disease (PMD) is an X-linked neurological disorder characterized by dysmyelination in the central nervous system (CNS). Recently mutations of the myelin proteolipid protein (PLP) gene which encodes both PLP and its isoform, DM-20 generated by alternative splicing, have been demonstrated in PMD patients. We analyzed the seven exons of the PLP gene of a Japanese boy affected with PMD by direct sequencing and identified an insertion event in exon VII of the PLP gene. This mutation was also present in his carrier mother, but was absent in ninety-five X chromosomes of normal Japanese. The frame-shift mutation leads to the production of truncated PLP with altered carboxyl terminal amino acid sequences, resulting in considerable change of the structure of PLP and DM-20 necessary for functional purposes. This is the first report of a mutation in exon VII of the PLP gene associated with PMD.

    Human molecular genetics 1993;2;12;2187-9

  • Identification of a new polymorphism in the human proteolipid protein gene.

    Poduslo SE, Decker P, Astle H, Kurth J and LaBate M

    Department of Neurology, Texas Tech University Health Sciences Center, Lubbock 79430.

    A polymorphism in the gene for proteolipid protein has been identified, using amplification by the polymerase chain reaction, restriction enzyme digestion, and fragment separation by polyacrylamide gel electrophoresis. The polymorphism is located in the transcribed 3'-untranslated region, a region with potential regulatory signals. The mutation consists of a single base pair insertion into a Hae III restriction site, producing a larger rare fragment of 409 bp as compared with the more frequent 325 bp fragment. The gene for proteolipid protein is on the X chromosome; thus the males are hemizygous for the rare allele and the females are heterozygous carriers. The polymorphism occurs with a frequency of 0.046 in a population of European origin and also has a rare frequency in multiple sclerosis patients.

    Neurochemistry international 1993;23;5;413-7

  • New variant in exon 3 of the proteolipid protein (PLP) gene in a family with Pelizaeus-Merzbacher disease.

    Pratt VM, Trofatter JA, Larsen MB, Hodes ME and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School Medicine Indianapolis 46202-5251.

    A C--greater than G transversion has been found in exon 3 of the PLP gene of affected males and their mother in a single sibship with Pelizaeus-merzbacher disease (PMD). The transversion should not result in an amino acid change in the protein but it does result in the loss of a HaeIII restriction endonuclease cleavage site. It is concordant with the disease in this family. One-hundred-ten unrelated X chromosomes are negative for this mutation. No other sequence defect was found in the PLP exons of the affected males. The cause of disease in this family remains unknown, but the association between this rare mutation and PMD is intriguing. The mutation can serve as a marker for following segregation of the PLP gene.

    American journal of medical genetics 1992;43;3;642-6

  • Complete deletion of the proteolipid protein gene (PLP) in a family with X-linked Pelizaeus-Merzbacher disease.

    Raskind WH, Williams CA, Hudson LD and Bird TD

    Department of Medicine, University of Washington School of Medicine, Seattle 98195.

    Pelizaeus-Merzbacher disease (PMD) is an X-linked neurologic disorder characterized by dysmyelination in the central nervous system. Proteolipid protein (PLP), a major structural protein of myelin, is coded on the X chromosome. It has been postulated that a defect in the PLP gene is responsible for PMD. Different single-nucleotide substitutions have been found in conserved regions of the PLP gene of four unrelated PMD patients. Novel Southern blot patterns suggested a complex rearrangement in a fifth family. Linkage to PLP has been shown in others. We evaluated the PLP locus in a four-generation family with two living males affected with X-linked PMD. Analysis of DNA from the affected males revealed complete absence of a band, with PLP probes encompassing the promoter region, the entire coding region, and the 3' untranslated region and spanning at least 29 kb of genomic DNA. DNA from unaffected relatives gave the expected band pattern. Two obligate and one probable carrier women were hemizygous for the PLP locus by dosage analysis. Although it is unlikely, the previously described point mutations in PLP could represent polymorphisms. The finding of complete deletion of the PLP gene in our family is a stronger argument that mutations in PLP are responsible for X-linked PMD.

    Funded by: NCI NIH HHS: CA 16448

    American journal of human genetics 1991;49;6;1355-60

Pubmed - other

  • Differences in endoplasmic-reticulum quality control determine the cellular response to disease-associated mutants of proteolipid protein.

    Roboti P, Swanton E and High S

    Faculty of Life Sciences, The University of Manchester, Oxford Road, Manchester M13 9PT, UK.

    Missense mutations in human PLP1, the gene encoding myelin proteolipid protein (PLP), cause dysmyelinating Pelizaeus-Merzbacher disease of varying severity. Although disease pathology has been linked to retention of misfolded PLP in the endoplasmic reticulum (ER) and induction of the unfolded protein response (UPR), the molecular mechanisms that govern phenotypic heterogeneity remain poorly understood. To address this issue, we examined the cellular response to missense mutants of PLP that are associated with distinct disease phenotypes. We found that the mild-disease-associated mutants, W162L and G245A, were cleared from the ER comparatively quickly via proteasomal degradation and/or ER exit. By contrast, the more ;aggressive' A242V mutant, which causes severe disease, was significantly more stable, accumulated at the ER and resulted in a specific activation of the UPR. On the basis of these findings, we propose that the rate at which mutant PLP proteins are cleared from the ER modulates disease severity by determining the extent to which the UPR is activated.

    Funded by: Wellcome Trust

    Journal of cell science 2009;122;Pt 21;3942-53

  • Neuronal loss in Pelizaeus-Merzbacher disease differs in various mutations of the proteolipid protein 1.

    Sima AA, Pierson CR, Woltjer RL, Hobson GM, Golden JA, Kupsky WJ, Schauer GM, Bird TD, Skoff RP and Garbern JY

    Department of Pathology, School of Medicine, Wayne State University, Detroit, MI, USA.

    Mutations affecting proteolipid protein 1 (PLP1), the major protein in central nervous system myelin, cause the X-linked leukodystrophy Pelizaeus-Merzbacher disease (PMD). We describe the neuropathologic findings in a series of eight male PMD subjects with confirmed PLP1 mutations, including duplications, complete gene deletion, missense and exon-skipping. While PLP1 mutations have effects on oligodendrocytes that result in mutation-specific degrees of dysmyelination, our findings indicate that there are also unexpected effects in the central nervous system resulting in neuronal loss. Although length-dependent axonal degeneration has been described in PLP1 null mutations, there have been no reports on neuronal degeneration in PMD patients. We now demonstrate widespread neuronal loss in PMD. The patterns of neuronal loss appear to be dependent on the mutation type, suggesting selective vulnerability of neuronal populations that depends on the nature of the PLP1 disturbance. Nigral neurons, which were not affected in patients with either null or severe misfolding mutations, and thalamic neurons appear particularly vulnerable in PLP1 duplication and deletion patients, while hippocampal neuronal loss was prominent in a patient with complete PLP1 gene deletion. All subjects showed cerebellar neuronal loss. The patterns of neuronal involvement may explain some clinical findings, such as ataxia, being more prominent in PMD than in other leukodystrophies. While the precise pathogenetic mechanisms are not known, these observations suggest that defective glial functions contribute to neuronal pathology.

    Funded by: NCRR NIH HHS: P20 RR 020173-01, P20 RR020173; NINDS NIH HHS: NS 043783, R01 NS043783, R01 NS058978

    Acta neuropathologica 2009;118;4;531-9

  • PLP1 gene duplication causes overexpression and alteration of the PLP/DM20 splicing balance in fibroblasts from Pelizaeus-Merzbacher disease patients.

    Regis S, Grossi S, Corsolini F, Biancheri R and Filocamo M

    Laboratorio Diagnosi Pre-Postnatale Malattie Metaboliche, Istituto G. Gaslini, Largo G. Gaslini 5, 16147 Genova, Italy.

    The PLP1 gene encodes two protein isoforms (PLP and DM20) which represent the predominant protein portion in myelin of the central nervous system. The two products are generated from the same primary transcript by alternative splicing. Defects of the PLP1 gene cause Pelizaeus-Merzbacher disease (PMD) or X-linked spastic paraplegia type 2 (SPG2). Duplication of the PLP1 gene is the most frequent gene defect, usually responsible for the classic form of PMD. To investigate the effects of PLP1 gene over dosage on gene expression, we analysed the PLP/DM20 expression profile in fibroblasts from three PMD patients with a PLP1 gene duplication. Gene expression was evaluated by real-time PCR using two different PLP1 amplicons and two different reference genes (GAPDH and GUSB). Fibroblasts from the three patients showed a 4-5 fold increase of PLP1 gene expression compared to fibroblasts from three normal controls. The contribution of the two alternatively spliced transcript isoforms (PLP and DM20) to the whole PLP1 gene expression was investigated using a DM20-specific amplicon. The three patients showed a decrease of the DM20/(DM20+PLP) ratio in comparison to the three normal controls, suggesting a prominent contribution of the PLP transcript to the PLP1 gene overexpression detected in the patients. Therefore, PLP1 gene duplication seems to result both in overexpression and in a shift of the PLP/DM20 splicing balance in direction of the PLP isoform.

    Funded by: Telethon: GTB07001

    Biochimica et biophysica acta 2009;1792;6;548-54

  • Arena syndrome is caused by a missense mutation in PLP1.

    Stevenson RE, Tarpey P, May MM, Stratton MR and Schwartz CE

    JC Self Research Institute of Human Genetics, Greenwood Genetic Center, Greenwood, South Carolina 29646, USA. res@ggc.org

    American journal of medical genetics. Part A 2009;149A;5;1081

  • Variable expression of a novel PLP1 mutation in members of a family with Pelizaeus-Merzbacher disease.

    Fattal-Valevski A, DiMaio MS, Hisama FM, Hobson GM, Davis-Williams A, Garbern JY, Mahoney MJ, Kolodny EH and Pastores GM

    Institute for Child Development and Pediatric Neurology Unit, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.

    Pelizaeus-Merzbacher disease is a rare X-linked disorder caused by mutations of the proteolipid protein 1 gene that encodes a structural component of myelin. It is characterized by progressive psychomotor delay, nystagmus, spastic quadriplegia, and cerebellar ataxia. Variable clinical expression was seen in 5 members of a family bearing a novel missense mutation in proteolipid protein 1, c.619T>C. Symptomatic patients included a 6-year-old girl, her younger brother, and their maternal uncle, a 29-year-old college graduate initially diagnosed with cerebral palsy; their brain magnetic resonance imaging studies showed diffuse dysmyelination. The mother had a history of delayed walking, achieved independently by age 3; she and the maternal grandmother were asymptomatic on presentation. Review of clinical information and family history led to consideration of Pelizaeus-Merzbacher disease. Subsequent identification of the causal mutation enabled preimplantation genetic diagnosis and the birth of an unaffected child.

    Funded by: NCRR NIH HHS: 5P20RR020173; NINDS NIH HHS: 1R01NS043783

    Journal of child neurology 2009;24;5;618-24

  • Heterogeneous nuclear ribonucleoproteins H and F regulate the proteolipid protein/DM20 ratio by recruiting U1 small nuclear ribonucleoprotein through a complex array of G runs.

    Wang E and Cambi F

    Department of Neurology, University of Kentucky, Lexington, Kentucky 40536, USA.

    In this study, we sought to investigate the mechanism by which heterogeneous nuclear ribonucleoprotein (hnRNP) H and F regulate proteolipid protein (PLP)/DM20 alternative splicing. G-rich sequences in exon 3B, G1 and M2, are required for hnRNPH- and F-mediated regulation of the PLP/DM20 ratio and, when placed between competing 5' splice sites in an alpha-globin minigene, direct hnRNPH/F-regulated alternative splicing. In contrast, the activity of the intronic splicing enhancer, which is necessary for PLP splicing, is only modestly reduced by removal of hnRNPH/F both in PLP and alpha-globin gene context. In vivo, hnRNPH reversed reduction of DM20 splicing induced by hnRNPH/F removal, whereas hnRNPF had little effect. Tethering of the MS2-hnRNPH fusion protein downstream of the DM20 5' splice site increased DM20 splicing, whereas MS2-hnRNPF did not. Binding of U1 small nuclear ribonucleoprotein (U1snRNP) to DM20 is greatly impaired by mutation of G1 and M2 and depletion of hnRNPH and F. Reconstitution of hnRNPH/F-depleted extracts with either hnRNPH or F restored U1snRNP binding. We conclude that hnRNPH and F regulate DM20 splicing by recruiting U1snRNP and that hnRNPH plays a primary role in DM20 splice site selection in vivo. Decreased expression of hnRNPH/F in differentiated oligodendrocytes may regulate the PLP/DM20 ratio by reducing DM20 5' splice site recognition by U1snRNP.

    Funded by: NCRR NIH HHS: P20 RR020171; NINDS NIH HHS: R01NS053905

    The Journal of biological chemistry 2009;284;17;11194-204

  • Proteolipid protein 1 gene mutation in nine patients with Pelizaeus-Merzbacher disease.

    Wang JM, Wu Y, Wang HF, Deng YH, Yang YL, Qin J, Li XY, Wu XR and Jiang YW

    Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.

    Background: Pelizaeus-Merzbacher disease (PMD) is a rare X-linked recessive disorder with symptoms including nystagmus, impaired motor development, ataxia, and progressive spasticity. The proteolipid protein 1 (PLP1) gene is the only pathogenic gene of PMD. Duplication of the PLP1 gene is the most frequent gene defect, accounting for 50%-70% of PMD cases, whereas point mutations in the coding sequence or the splice sites account for 10%-25% of PMD cases. This study aimed to identify PLP1 mutations in nine unrelated Chinese patients (P1-9) with PMD, and 14 subjects from the family of patient 2 were also described.

    Methods: Genomic DNA was extracted from peripheral blood samples. Gene dosage was determined using the multiplex ligation-dependent probe amplification (MLPA). All 7 exons and exon-intron boundaries of the PLP1 gene were amplified and analyzed using direct DNA sequencing.

    Results: Of these nine patients, there were four transitional, four classical, and one connatal PMD according to their clinical and radiological presentations. PLP1 duplications were identified in patients 1-7 with PMD. Their mothers were PLP1 duplications carriers as well. Both duplication carriers and normal genotypes of PLP1 were identified in the family members of patient 2. A c.517C > T (p. P173S) hemizygous missense mutation in exon 4 was found in patient 8 with PMD, and his mother was shown to be a heterozygote of this mutation.

    Conclusions: We identified seven genomic duplications and one missense mutation (p. P173S) of the PLP1 gene in eight Chinese patients with PMD. This is the report about PLP1 mutations in PMD patients from the mainland of China.

    Funded by: FIC NIH HHS: D43 TW06176

    Chinese medical journal 2008;121;17;1638-42

  • Origin of CD11b+ macrophage-like cells in the CNS of PLP-overexpressing mice: low influx of haematogenous macrophages and unchanged blood-brain-barrier in the optic nerve.

    Ip CW, Kohl B, Kleinschnitz C, Reuss B, Nave KA, Kroner A and Martini R

    Department of Neurology, Developmental Neurobiology, University of Wuerzburg, Josef-Schneider Str. 11, D-97080 Wuerzburg, Germany.

    We have recently reported that overexpression of proteolipid protein in oligodendrocytes leads to a pathologically relevant increase of both CD8+ T-lymphocytes and CD11b+ cells in the CNS. We now focussed on the origin of the CD11b+ cells in the optic nerve, a well established structure for the analysis of the mutant, using bone marrow chimeric mice. Although there is an age-related increase in CD11b+ cells in the myelinated part of the optic nerve of the mutants, the percentage of infiltrating cells was not increased, but enhanced proliferation was detectable. In the non-myelinated optic nerve head, the rate of infiltrating CD11b+ cells and albumin extravasation was high in both genotypes. However, albumin extravasation was also high in the rostral myelinated part, where CD11b+ cell influx was low. Our study demonstrates an intrinsic origin of CD11b+ cells in the presence of an unchanged blood-brain-barrier in a CNS myelin mutant.

    Molecular and cellular neurosciences 2008;38;4;489-94

  • PLP1 splicing abnormalities identified in Pelizaeus-Merzbacher disease and SPG2 fibroblasts are associated with different types of mutations.

    Bonnet-Dupeyron MN, Combes P, Santander P, Cailloux F, Boespflug-Tanguy O and Vaurs-Barrière C

    INSERM, U384, Faculté de Médecine de Clermont-Ferrand, Clermont-Ferrand, France.

    The proteolipid protein 1 (PLP1) gene encodes the two major proteins of the central nervous system (CNS) myelin: PLP and DM20. PLP1 gene mutations are associated with a large spectrum of X-linked dysmyelinating disorders ranging from hypomyelinating leukodystrophy, Pelizaeus-Merzbacher disease (PMD), to spastic paraplegia (SPG2) according to the nature of the mutation. Genetic heterogeneity exists and mutations in the gap-junction alpha 12 (GJA12) gene have been related to PMD. About 20% of patients with the PMD phenotype remain without mutation in these two genes and are classified as affected by Pelizaeus-Merzbacher-like disease (PMLD). To study PLP1 splicing abnormalities, we analyzed PLP/DM20 transcripts from nerves and/or skin cultured fibroblasts of 14 PMD/SPG2 patients carrying different PLP1 mutations and 20 PMLD patients. We found that various types of PLP1 mutations result in missplicing, including one considered as a missense in exon 2 and a nucleotide substitution in intron 3 outside the classical donor and acceptor splicing sites. Moreover, we demonstrated for two patients that the fibroblast transcript pattern was in accordance with the one observed in the corresponding CNS/peripheral nervous system (PNS) tissues. Finally, we observed no abnormal splicing in fibroblasts of 20 PMLD patients tested; suggesting that PLP1 gene splicing abnormalities, potentially caused by undetected intronic mutations, are either not involved or are very rarely implicated in the PMLD phenotype. These results confirm that fibroblasts are reliable, accessible cells useful in detecting PLP1 transcript abnormalities, better characterizing the functional consequences of PLP1 mutations for genotype-phenotype correlation, characterizing new PLP1 splicing regulatory elements, and identifying PLP1 mutations undetected by conventional PLP1 screening.

    Human mutation 2008;29;8;1028-36

  • Identification of proteolipid protein 1 gene duplication by multiplex ligation-dependent probe amplification: first report of genetically confirmed family of Pelizaeus-Merzbacher disease in Korea.

    Kim SJ, Yoon JS, Baek HJ, Suh SI, Bae SY, Cho HJ and Ki CS

    Department of Physical Medicine and Rehabilitation, College of Medicine, Korea University, Seoul, Korea.

    Pelizaeus-Merzbacher disease (PMD) is a rare X-linked recessive disorder with a prototype of a dysmyelinating leukodystrophy that is caused by a mutation in the proteolipid protein 1 (PLP1) gene on the long arm of the X chromosome in band Xq22. This mutation results in abnormal expression or production of PLP. We here present a Korean boy with spastic quadriplegia, horizontal nystagmus, saccadic gaze, intentional tremor, head titubation, ataxia, and developmental delay. The brain magnetic resonance imaging (MRI) showed abnormally high signal intensities in the white matter tract, including a subcortical U fiber on the T2-weighted and fluid attenuated inversion recovery (FLAIR) image. The chromosomal analysis was normal; however, duplication of the PLP1 gene in chromosome Xq22 was detected when the multiplex ligation-dependent probe amplification (MLPA) method was used. We also investigated the pedigree for a genetic study related to PMD. This case suggests that the duplication mutation of the PLP1 gene in patients with PMD results in a mild clinical form of the disorder that mimics the spastic quadriplegia of cerebral palsy.

    Journal of Korean medical science 2008;23;2;328-31

  • Genotype-phenotype correlation in five Pelizaeus-Merzbacher disease patients with PLP1 gene duplications.

    Regis S, Biancheri R, Bertini E, Burlina A, Lualdi S, Bianco MG, Devescovi R, Rossi A, Uziel G and Filocamo M

    Diagnosi Pre-Postnatale Malattie Metaboliche Laboratory, Children Hospital IRCCS G. Gaslini, Genoa, Italy.

    Pelizaeus-Merzbacher disease (PMD) is an X-linked myelination disorder most frequently caused by duplication of a genomic segment of variable length containing the PLP1 gene. We studied five PMD male patients affected by the classic PMD form carrying a PLP1 gene duplication. On the basis of clinical and neuroradiological features, two of the five patients appeared to be the most severely affected. In order to establish a possible genotype-phenotype correlation, the extent of the duplication was determined in each patient and in the respective mother by quantifying the copy number of genomic markers surrounding the PLP1 gene by a real-time PCR-based approach. Duplications, ranging in size from 167-195 to 580-700 kb, were in the same genomic interval of the majority of the reported duplications. The extent of the duplicated genomic segments does not correlate with the clinical severity. Interestingly enough, each duplication had one of the two breakpoints in or near to low copy repeats (LCRs), supporting recent evidence concerning a possible role of LCRs in the generation of the duplications in PMD.

    Funded by: Telethon: GTF04002

    Clinical genetics 2008;73;3;279-87

  • No association between the oligodendrocyte-related gene PLP1 and schizophrenia in the Japanese population.

    Aleksic B, Ikeda M, Ishihara R, Saito S, Inada T, Iwata N and Ozaki N

    Department of Psychiatry, Graduate School of Medicine, Nagoya University, Showa-ku, Tsurumai-Cho, 65, Nagoya, Aichi 466-8550, Japan. branko@med.nagoya-u.ac.jp

    PLP1 is one of the major myelin-related genes. A large body of expression-based studies showed significantly lower levels of the PLP1 messenger ribonucleic acid (mRNA) transcripts in schizophrenia. Moreover, one family-based study identified a weak association signal in a male subset using 487 Chinese family trios. We carried out a population-based association study between PLP1 and schizophrenia in 1,640 subjects. Our data does not support genetic variation in close vicinity or within PLP1 locus as a susceptibility factor.

    Journal of human genetics 2008;53;9;863-6

  • A common mechanism of PLP/DM20 misfolding causes cysteine-mediated endoplasmic reticulum retention in oligodendrocytes and Pelizaeus-Merzbacher disease.

    Dhaunchak AS and Nave KA

    Department of Neurogenetics, Max Planck Institute of Experimental Medicine, D-37075 Göttingen, Germany.

    A large number of mutations in the human PLP1 gene lead to abnormal myelination and oligodendrocyte death in Pelizaeus-Merzbacher disease (PMD). Here we show that a major subgroup of PMD mutations that map into the extracellular loop region of PLP/DM20 leads to the failure of oligodendrocytes to form the correct intramolecular disulfide bridges. This leads to abnormal protein cross-links and endoplasmic reticulum retention and activates the unfolded protein response. Importantly, surface expression of mutant PLP/DM20 can be restored and the unfolded protein response can be reverted by the removal of two cysteines. Thus, covalent protein cross-links emerge as a cause, rather than as a consequence, of endoplasmic reticulum retention.

    Proceedings of the National Academy of Sciences of the United States of America 2007;104;45;17813-8

  • The role of hereditary spastic paraplegia related genes in multiple sclerosis. A study of disease susceptibility and clinical outcome.

    DeLuca GC, Ramagopalan SV, Cader MZ, Dyment DA, Herrera BM, Orton S, Degenhardt A, Pugliatti M, Sadovnick AD, Sotgiu S and Ebers GC

    University Dept. of Clinical Neurology, University of Oxford, Radcliffe Infirmary, Woodstock Rd, Oxford, OX2 6LE, UK.

    Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system unsurpassed for its variability in disease outcome. It has been observed that axonal loss in MS is significant and that irreversible clinical disability relates to such axonal loss. The clinical similarities between Hereditary Spastic Paraplegia (HSP) and progressive MS, along with their analogous profiles of axonal loss in the long tracts, make the genes known to cause HSP biologically relevant candidates for the study of clinical outcome in MS. A cohort of sporadic MS cases and a set of unaffected controls were used to determine the role of HSP genes on MS susceptibility and disease severity. The MS cases were taken from opposite extremes of the putative distribution of long-term outcome using the most stringent clinical criteria to date. Genotyping the two sets of MS patients and controls could not provide any evidence to suggest that genes involved in the pathogenesis of HSP (Paraplegin, NIPA1, KIF5A, HSPD1, Atlastin, Spartin, Spastin, PLP1, L1CAM, Maspardin and BSCL2) play a role in susceptibility to, or modifying the course of, MS, although small effects of these genes cannot be ruled out.

    Journal of neurology 2007;254;9;1221-6

  • Steroid-responsive neurologic relapses in a child with a proteolipid protein-1 mutation.

    Gorman MP, Golomb MR, Walsh LE, Hobson GM, Garbern JY, Kinkel RP, Darras BT, Urion DK and Eksioglu YZ

    Department of Neurology, Children's Hospital, Boston, MA 02115, USA.

    A 10-year-old boy developed corticosteroid-responsive relapsing neurologic signs, including nystagmus and ataxia. MRI revealed multifocal T2 white matter hyperintensities; several were gadolinium-enhancing. CSF contained oligoclonal bands. Although the patient met criteria for multiple sclerosis (MS), the proteolipid protein-1 gene (PLP1) contained a mutation in exon 3B (c.409C>T), predicting a tryptophan-for-arginine substitution. This case raises questions about the role of inflammation in PLP1-related disorders and, conversely, PLP1 mutations in MS.

    Funded by: NCRR NIH HHS: P20 RR-020173-01; NINDS NIH HHS: 1R01NS043783, K23 NS8024

    Neurology 2007;68;16;1305-7

  • Novel alternatively spliced endoplasmic reticulum retention signal in the cytoplasmic loop of Proteolipid Protein-1.

    Southwood C, Olson K, Wu CY and Gow A

    Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.

    Increased awareness about the importance of protein folding and trafficking to the etiology of gain-of-function diseases has driven extensive efforts to understand the cell and molecular biology underlying the life cycle of normal secretory pathway proteins and the detrimental effects of abnormal proteins. In this regard, the quality-control machinery in the endoplasmic reticulum (ER) has emerged as a major mechanism by which cells ensure that secreted and transmembrane proteins either adopt stable secondary, tertiary, and quaternary structures or are retained in the ER and degraded. Here we examine cellular and molecular aspects of ER retention in transfected fibroblasts expressing missense mutations in the Proteolipid Protein-1 (PLP1) gene that cause mild or severe forms of neurodegenerative disease in humans. Mild mutations cause protein retention in the ER that is partially dependent on the presence of a cytoplasmically exposed heptapeptide, KGRGSRG. In contrast, retention associated with severe mutations occurs independently of this peptide. Accordingly, the function of this novel heptapeptide has a significant impact on pathogenesis and provides new insight into the functions of the two splice isoforms encoded by the PLP1 gene, PLP1 and DM-20.

    Funded by: CSR NIH HHS: RG2891; NINDS NIH HHS: NS43783, R01 NS043783

    Journal of neuroscience research 2007;85;3;471-8

  • Role of genomic architecture in PLP1 duplication causing Pelizaeus-Merzbacher disease.

    Lee JA, Inoue K, Cheung SW, Shaw CA, Stankiewicz P and Lupski JR

    Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, Houston, TX 77030, USA.

    Genomic architecture, higher order structural features of the human genome, can provide molecular substrates for recurrent sub-microscopic chromosomal rearrangements, or may result in genomic instability by forming structures susceptible to DNA double-strand breaks. Pelizaeus-Merzbacher disease (PMD) is a genomic disorder most commonly arising from genomic duplications of the dosage-sensitive proteolipid protein gene (PLP1). Unlike many other genomic disorders that result from non-allelic homologous recombination utilizing flanking low-copy repeats (LCRs) as substrates, generating a common and recurrent rearrangement, the breakpoints of PLP1 duplications have been reported not to cluster, yielding duplicated genomic segments of varying lengths. This suggests a distinct molecular mechanism underlying PLP1 duplication events. To determine whether structural features of the genome also facilitate PLP1 duplication events, we analyzed extensively the genomic architecture of the PLP1 region and defined several novel LCRs (LCR-PMDs). Array comparative genomic hybridization showed that PLP1 duplication sizes differed, but revealed a subgroup of patients with apparently similar PLP1 duplication breakpoints. Pulsed-field gel electrophoresis analysis using probes adjacent to the LCR-PMDs detected unique recombination-specific junction fragments in 12 patients, enabled us to associate the LCR-PMDs with breakpoint regions, and revealed rearrangements inconsistent with simple tandem duplications in four patients. Two-color fluorescence in situ hybridization was consistent with directly oriented duplications. Our study provides evidence that PLP1 duplication events may be stimulated by LCRs, possibly non-homologous pairs at both the proximal and distal breakpoints in some cases, and further supports an alternative role of genomic architecture in rearrangements responsible for genomic disorders.

    Funded by: NICHD NIH HHS: HD 2406407, P01 HD38420; NINDS NIH HHS: R01 NS27042

    Human molecular genetics 2006;15;14;2250-65

  • Spastic paraplegia type 2 associated with axonal neuropathy and apparent PLP1 position effect.

    Lee JA, Madrid RE, Sperle K, Ritterson CM, Hobson GM, Garbern J, Lupski JR and Inoue K

    Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.

    Objective: To report an association between spastic paraplegia type 2 with axonal peripheral neuropathy and apparent proteolipid protein gene (PLP1) silencing in a family.

    Methods: Pulsed-field gel electrophoresis, custom array comparative genomic hybridization, and semi-quantitative multiplex polymerase chain reaction analyses were used to examine the PLP1 genomic region.

    Results: Electrodiagnostic studies and a sural nerve biopsy showed features of a dystrophic axonal neuropathy. Molecular studies identified a small duplication downstream of PLP1.

    Interpretation: We propose the duplication to result in PLP1 gene silencing by virtue of a position effect. Our observations suggest that genomic rearrangements that do not include PLP1 coding sequences should be considered as yet another potential mutational mechanism underlying PLP1-related dysmyelinating disorders.

    Funded by: NCRR NIH HHS: 1P20RR020173; NICHD NIH HHS: P01 HD38420; NINDS NIH HHS: R01 NS27042

    Annals of neurology 2006;59;2;398-403

  • Splice-site contribution in alternative splicing of PLP1 and DM20: molecular studies in oligodendrocytes.

    Hobson GM, Huang Z, Sperle K, Sistermans E, Rogan PK, Garbern JY, Kolodny E, Naidu S and Cambi F

    Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Nemours Children's Clinic, Wilmington, Delaware, USA. ghobson@nemours.org

    Mutations in the proteolipid protein 1 (PLP1) gene cause the X-linked dysmyelinating diseases Pelizaeus-Merzbacher disease (PMD) and spastic paraplegia 2 (SPG2). We examined the severity of the following mutations that were suspected of affecting levels of PLP1 and DM20 RNA, the alternatively spliced products of PLP1: c.453G>A, c.453G>T, c.453G>C, c.453+2T>C, c.453+4A>G, c.347C>A, and c.453+28_+46del (the old nomenclature did not include the methionine codon: G450A, G450T, G450C, IVS3+2T>C, IVS3+4A>G, C344A, and IVS3+28-+46del). These mutations were evaluated by information theory-based analysis and compared with mRNA expression of the alternatively spliced products. The results are discussed relative to the clinical severity of disease. We conclude that the observed PLP1 and DM20 splicing patterns correlated well with predictions of information theory-based analysis, and that the relative strength of the PLP1 and DM20 donor splice sites plays an important role in PLP1 alternative splicing.

    Funded by: NCRR NIH HHS: 1P20RR020173-01; NIEHS NIH HHS: ES 10855-02

    Human mutation 2006;27;1;69-77

  • Heterogeneous duplications in patients with Pelizaeus-Merzbacher disease suggest a mechanism of coupled homologous and nonhomologous recombination.

    Woodward KJ, Cundall M, Sperle K, Sistermans EA, Ross M, Howell G, Gribble SM, Burford DC, Carter NP, Hobson DL, Garbern JY, Kamholz J, Heng H, Hodes ME, Malcolm S and Hobson GM

    Clinical and Molecular Genetics, Institute of Child Health, London.

    We describe genomic structures of 59 X-chromosome segmental duplications that include the proteolipid protein 1 gene (PLP1) in patients with Pelizaeus-Merzbacher disease. We provide the first report of 13 junction sequences, which gives insight into underlying mechanisms. Although proximal breakpoints were highly variable, distal breakpoints tended to cluster around low-copy repeats (LCRs) (50% of distal breakpoints), and each duplication event appeared to be unique (100 kb to 4.6 Mb in size). Sequence analysis of the junctions revealed no large homologous regions between proximal and distal breakpoints. Most junctions had microhomology of 1-6 bases, and one had a 2-base insertion. Boundaries between single-copy and duplicated DNA were identical to the reference genomic sequence in all patients investigated. Taken together, these data suggest that the tandem duplications are formed by a coupled homologous and nonhomologous recombination mechanism. We suggest repair of a double-stranded break (DSB) by one-sided homologous strand invasion of a sister chromatid, followed by DNA synthesis and nonhomologous end joining with the other end of the break. This is in contrast to other genomic disorders that have recurrent rearrangements formed by nonallelic homologous recombination between LCRs. Interspersed repetitive elements (Alu elements, long interspersed nuclear elements, and long terminal repeats) were found at 18 of the 26 breakpoint sequences studied. No specific motif that may predispose to DSBs was revealed, but single or alternating tracts of purines and pyrimidines that may cause secondary structures were common. Analysis of the 2-Mb region susceptible to duplications identified proximal-specific repeats and distal LCRs in addition to the previously reported ones, suggesting that the unique genomic architecture may have a role in nonrecurrent rearrangements by promoting instability.

    Funded by: NCRR NIH HHS: P20 RR-020173-01, P20 RR020173; NINDS NIH HHS: NS043783, R01 NS043783; Wellcome Trust

    American journal of human genetics 2005;77;6;966-87

  • Primary progressive multiple sclerosis as a phenotype of a PLP1 gene mutation.

    Warshawsky I, Rudick RA, Staugaitis SM and Natowicz MR

    Department of Clinical Pathology, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.

    We report a 49-year-old woman with a history of progressive gait disturbance, white matter disease, and cerebrospinal fluid immunoglobulin abnormalities who met criteria for primary progressive multiple sclerosis and whose son died at age 10 years of an unknown congenital neurodevelopmental disorder. Sequencing of the proteolipid protein 1 gene showed a novel mutation, Leu30Arg (c.89TG), in the mother and son. Pelizaeus-Merzbacher disease is the cause of death in the son and explains the mother's adult-onset neurological disorder. This case goes against dogma that mothers of severely affected sons are asymptomatic as adults and expands the differential diagnosis of primary progressive multiple sclerosis to include proteolipid protein 1 gene mutations.

    Annals of neurology 2005;58;3;470-3

  • Disease-associated mutations cause premature oligomerization of myelin proteolipid protein in the endoplasmic reticulum.

    Swanton E, Holland A, High S and Woodman P

    Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK. lisa.swanton@man.ac.uk

    Pelizaeus-Merzbacher disease (PMD) is a dysmyelinating disease caused by mutations, deletions, or duplications of the proteolipid protein (PLP) gene. Mutant forms of PLP are retained in the endoplasmic reticulum (ER), and the resulting accumulation of mutant protein is thought to be a direct cause of oligodendrocyte cell death, which is the primary clinical feature of PMD. The molecular mechanisms underlying the toxicity of mutant PLP are however currently unknown. We report here that PMD-linked mutations of PLP are associated with the accelerated assembly of the protein into stable homooligomers that resemble mature, native PLP. Thus although WT PLP forms stable oligomers after an extended maturation period, most likely at the cell surface, mutant forms of PLP rapidly assemble into such oligomers at the ER. Using PLP mutants associated with diseases of varying severity, we show that the formation of stable oligomers correlates with the development of PMD. Based on these findings, we propose that the premature oligomerization of PLP in the ER of oligodendrocytes contributes to the pathology of PMD.

    Funded by: Biotechnology and Biological Sciences Research Council: BBS/B/02568, SF16973

    Proceedings of the National Academy of Sciences of the United States of America 2005;102;12;4342-7

  • The DNA sequence of the human X chromosome.

    Ross MT, Grafham DV, Coffey AJ, Scherer S, McLay K, Muzny D, Platzer M, Howell GR, Burrows C, Bird CP, Frankish A, Lovell FL, Howe KL, Ashurst JL, Fulton RS, Sudbrak R, Wen G, Jones MC, Hurles ME, Andrews TD, Scott CE, Searle S, Ramser J, Whittaker A, Deadman R, Carter NP, Hunt SE, Chen R, Cree A, Gunaratne P, Havlak P, Hodgson A, Metzker ML, Richards S, Scott G, Steffen D, Sodergren E, Wheeler DA, Worley KC, Ainscough R, Ambrose KD, Ansari-Lari MA, Aradhya S, Ashwell RI, Babbage AK, Bagguley CL, Ballabio A, Banerjee R, Barker GE, Barlow KF, Barrett IP, Bates KN, Beare DM, Beasley H, Beasley O, Beck A, Bethel G, Blechschmidt K, Brady N, Bray-Allen S, Bridgeman AM, Brown AJ, Brown MJ, Bonnin D, Bruford EA, Buhay C, Burch P, Burford D, Burgess J, Burrill W, Burton J, Bye JM, Carder C, Carrel L, Chako J, Chapman JC, Chavez D, Chen E, Chen G, Chen Y, Chen Z, Chinault C, Ciccodicola A, Clark SY, Clarke G, Clee CM, Clegg S, Clerc-Blankenburg K, Clifford K, Cobley V, Cole CG, Conquer JS, Corby N, Connor RE, David R, Davies J, Davis C, Davis J, Delgado O, Deshazo D, Dhami P, Ding Y, Dinh H, Dodsworth S, Draper H, Dugan-Rocha S, Dunham A, Dunn M, Durbin KJ, Dutta I, Eades T, Ellwood M, Emery-Cohen A, Errington H, Evans KL, Faulkner L, Francis F, Frankland J, Fraser AE, Galgoczy P, Gilbert J, Gill R, Glöckner G, Gregory SG, Gribble S, Griffiths C, Grocock R, Gu Y, Gwilliam R, Hamilton C, Hart EA, Hawes A, Heath PD, Heitmann K, Hennig S, Hernandez J, Hinzmann B, Ho S, Hoffs M, Howden PJ, Huckle EJ, Hume J, Hunt PJ, Hunt AR, Isherwood J, Jacob L, Johnson D, Jones S, de Jong PJ, Joseph SS, Keenan S, Kelly S, Kershaw JK, Khan Z, Kioschis P, Klages S, Knights AJ, Kosiura A, Kovar-Smith C, Laird GK, Langford C, Lawlor S, Leversha M, Lewis L, Liu W, Lloyd C, Lloyd DM, Loulseged H, Loveland JE, Lovell JD, Lozado R, Lu J, Lyne R, Ma J, Maheshwari M, Matthews LH, McDowall J, McLaren S, McMurray A, Meidl P, Meitinger T, Milne S, Miner G, Mistry SL, Morgan M, Morris S, Müller I, Mullikin JC, Nguyen N, Nordsiek G, Nyakatura G, O'Dell CN, Okwuonu G, Palmer S, Pandian R, Parker D, Parrish J, Pasternak S, Patel D, Pearce AV, Pearson DM, Pelan SE, Perez L, Porter KM, Ramsey Y, Reichwald K, Rhodes S, Ridler KA, Schlessinger D, Schueler MG, Sehra HK, Shaw-Smith C, Shen H, Sheridan EM, Shownkeen R, Skuce CD, Smith ML, Sotheran EC, Steingruber HE, Steward CA, Storey R, Swann RM, Swarbreck D, Tabor PE, Taudien S, Taylor T, Teague B, Thomas K, Thorpe A, Timms K, Tracey A, Trevanion S, Tromans AC, d'Urso M, Verduzco D, Villasana D, Waldron L, Wall M, Wang Q, Warren J, Warry GL, Wei X, West A, Whitehead SL, Whiteley MN, Wilkinson JE, Willey DL, Williams G, Williams L, Williamson A, Williamson H, Wilming L, Woodmansey RL, Wray PW, Yen J, Zhang J, Zhou J, Zoghbi H, Zorilla S, Buck D, Reinhardt R, Poustka A, Rosenthal A, Lehrach H, Meindl A, Minx PJ, Hillier LW, Willard HF, Wilson RK, Waterston RH, Rice CM, Vaudin M, Coulson A, Nelson DL, Weinstock G, Sulston JE, Durbin R, Hubbard T, Gibbs RA, Beck S, Rogers J and Bentley DR

    The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK. mtr@sanger.ac.uk

    The human X chromosome has a unique biology that was shaped by its evolution as the sex chromosome shared by males and females. We have determined 99.3% of the euchromatic sequence of the X chromosome. Our analysis illustrates the autosomal origin of the mammalian sex chromosomes, the stepwise process that led to the progressive loss of recombination between X and Y, and the extent of subsequent degradation of the Y chromosome. LINE1 repeat elements cover one-third of the X chromosome, with a distribution that is consistent with their proposed role as way stations in the process of X-chromosome inactivation. We found 1,098 genes in the sequence, of which 99 encode proteins expressed in testis and in various tumour types. A disproportionately high number of mendelian diseases are documented for the X chromosome. Of this number, 168 have been explained by mutations in 113 X-linked genes, which in many cases were characterized with the aid of the DNA sequence.

    Funded by: NHGRI NIH HHS: U54 HG003273

    Nature 2005;434;7031;325-37

  • A family-based association study of PLP1 and schizophrenia.

    Qin W, Gao J, Xing Q, Yang J, Qian X, Li X, Guo Z, Chen H, Wang L, Huang X, Gu N, Feng G and He L

    Bio-X Life Science Research Center, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030, PR China.

    Recently, proteolipid protein 1 (PLP1) has been identified as downregulated in schizophrenia by quantitative PCR and other technologies. In this work we attempted to investigate the role of PLP1 in the etiology of schizophrenia using a family based association study in 487 Chinese Han family trios. The TDT for allelic association demonstrated that, in male, a weak association was detected in SNP rs475827 with p=0.0294, suggesting that the genetic polymorphisms within PLP1 in male are likely to confer an increased susceptibility to schizophrenia in the Chinese population.

    Neuroscience letters 2005;375;3;207-10

  • Seventeen novel PLP1 mutations in patients with Pelizaeus-Merzbacher disease.

    Hübner CA, Orth U, Senning A, Steglich C, Kohlschütter A, Korinthenberg R and Gal A

    Institute of Human Genetics, University Hospital Eppendorf, Hamburg, Germany. c.huebner@uke.uni-hamburg.de

    Pelizaeus-Merzbacher disease (PMD) is a rare X-chromosomal neurodegenerative disorder that affects primarily the white matter of the central nervous system and is caused by mutations of the PLP1 (proteolipid protein 1) gene. We performed mutation analysis of 133 male patients with suspected PMD. Following SSCP analysis of all coding exons of PLP1, we found most likely pathogenic mutations (single base substitutions and small rearrangements) including 17 novel sequence variants in 21 (15.8%) patients. Most patients with missense mutations had a severe phenotype. Twelve patients (9.0%) carried a duplication of the entire gene, as demonstrated by quantitative real-time PCR, and presented with a variable clinical phenotype including mild, classical, and severe courses of disease. Two patients had large deletions, spanning approximately 115 kb, that included the PLP1 gene. In total, we identified pathogenic mutations involving PLP1 in 35 (26.3%) of the 133 patients analyzed.

    Human mutation 2005;25;3;321-2

  • PLP1-related inherited dysmyelinating disorders: Pelizaeus-Merzbacher disease and spastic paraplegia type 2.

    Inoue K

    Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502, Japan. kinoue@ncnp.go.jp

    Pelizaeus-Merzbacher disease (PMD) and its allelic disorder, spastic paraplegia type 2 (SPG2), are among the best-characterized dysmyelinating leukodystrophies of the central nervous system (CNS). Both PMD and SPG2 are caused by mutations in the proteolipid protein 1 (PLP1) gene, which encodes a major component of CNS myelin proteins. Distinct types of mutations, including point mutations and genomic duplications and deletions, have been identified as causes of PMD/SPG2 that act through different molecular mechanisms. Studies of various PLP1 mutants in humans and animal models have shed light on the genomic, molecular, and cellular pathogeneses of PMD/SPG2. Recent discoveries include complex mutational mechanisms and associated disease phenotypes, novel cellular pathways that lead to the degeneration of oligodendrocytes, and genomic architectural features that result in unique chromosomal rearrangements. Here, I review the previous and current knowledge of the molecular pathogenesis of PMD/SPG2 and delineate future directions for PMD/SPG2 studies.

    Neurogenetics 2005;6;1;1-16

  • Mild Pelizaeus-Merzbacher disease caused by a point mutation affecting correct splicing of PLP1 mRNA.

    Hübner CA, Senning A, Orth U, Zerres K, Urbach H, Gal A and Rudnik-Schöneborn S

    Institute for Human Genetics, University Hospital Eppendorf, Hamburg, Germany.

    We describe a 28-year-old male patient with a mild course of Pelizaeus-Merzbacher disease (PMD) who presented with developmental delay in his second year of life and was able to walk until 12 years of age. Several computed tomography scans in infancy and youth were normal, the diagnosis of PMD was eventually suggested by magnetic resonance imaging at the age of 24 years. Analysis of the proteolipid protein gene (PLP1) revealed a nucleotide exchange (c.762G>T) at the 3' border of exon 6, which did not entail an amino acid exchange but adversely affected splicing. PCR analysis of fibroblast cDNA showed that c.762G>T resulted in partial skipping of exon 6 in the PLP1 mRNA. Exclusion of exon 6 does not alter the reading frame but leads to absence of amino acids 232-253 that constitute a main part of the fourth transmembrane helix of the PLP protein. Remarkably, residual wild-type splicing was also detected in the patient's cultured fibroblasts. This might explain the mild phenotype in this case, as exon 6 skipping mutations resulted in a severe course of disease in other patients.

    Neuroscience 2005;132;3;697-701

  • The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).

    Gerhard DS, Wagner L, Feingold EA, Shenmen CM, Grouse LH, Schuler G, Klein SL, Old S, Rasooly R, Good P, Guyer M, Peck AM, Derge JG, Lipman D, Collins FS, Jang W, Sherry S, Feolo M, Misquitta L, Lee E, Rotmistrovsky K, Greenhut SF, Schaefer CF, Buetow K, Bonner TI, Haussler D, Kent J, Kiekhaus M, Furey T, Brent M, Prange C, Schreiber K, Shapiro N, Bhat NK, Hopkins RF, Hsie F, Driscoll T, Soares MB, Casavant TL, Scheetz TE, Brown-stein MJ, Usdin TB, Toshiyuki S, Carninci P, Piao Y, Dudekula DB, Ko MS, Kawakami K, Suzuki Y, Sugano S, Gruber CE, Smith MR, Simmons B, Moore T, Waterman R, Johnson SL, Ruan Y, Wei CL, Mathavan S, Gunaratne PH, Wu J, Garcia AM, Hulyk SW, Fuh E, Yuan Y, Sneed A, Kowis C, Hodgson A, Muzny DM, McPherson J, Gibbs RA, Fahey J, Helton E, Ketteman M, Madan A, Rodrigues S, Sanchez A, Whiting M, Madari A, Young AC, Wetherby KD, Granite SJ, Kwong PN, Brinkley CP, Pearson RL, Bouffard GG, Blakesly RW, Green ED, Dickson MC, Rodriguez AC, Grimwood J, Schmutz J, Myers RM, Butterfield YS, Griffith M, Griffith OL, Krzywinski MI, Liao N, Morin R, Morrin R, Palmquist D, Petrescu AS, Skalska U, Smailus DE, Stott JM, Schnerch A, Schein JE, Jones SJ, Holt RA, Baross A, Marra MA, Clifton S, Makowski KA, Bosak S, Malek J and MGC Project Team

    The National Institutes of Health's Mammalian Gene Collection (MGC) project was designed to generate and sequence a publicly accessible cDNA resource containing a complete open reading frame (ORF) for every human and mouse gene. The project initially used a random strategy to select clones from a large number of cDNA libraries from diverse tissues. Candidate clones were chosen based on 5'-EST sequences, and then fully sequenced to high accuracy and analyzed by algorithms developed for this project. Currently, more than 11,000 human and 10,000 mouse genes are represented in MGC by at least one clone with a full ORF. The random selection approach is now reaching a saturation point, and a transition to protocols targeted at the missing transcripts is now required to complete the mouse and human collections. Comparison of the sequence of the MGC clones to reference genome sequences reveals that most cDNA clones are of very high sequence quality, although it is likely that some cDNAs may carry missense variants as a consequence of experimental artifact, such as PCR, cloning, or reverse transcriptase errors. Recently, a rat cDNA component was added to the project, and ongoing frog (Xenopus) and zebrafish (Danio) cDNA projects were expanded to take advantage of the high-throughput MGC pipeline.

    Funded by: PHS HHS: N01-C0-12400

    Genome research 2004;14;10B;2121-7

  • A case of complicated spastic paraplegia 2 due to a point mutation in the proteolipid protein 1 gene.

    Lee ES, Moon HK, Park YH, Garbern J and Hobson GM

    Department of Pediatrics, Yeungnam University Hospital, Daegu, South Korea.

    Pelizaeus-Merzbacher disease (PMD) is a rare X-linked dysmyelinating disorder resulting from mutation of the proteolipid protein gene (PLP1). Clinical features of PMD include progressive psychomotor developmental delay, nystagmus, spastic quadriplegia, dystonia, and cerebellar ataxia. PMD is clinically classified into three subtypes according to the severity of the disease: connatal, transitional, and classic forms. Patients with PMD have been identified with duplication, point mutations, and deletion of PLP1. In addition, spastic paraplegia 2 (SPG2) is allelic to PMD and typically caused by missense mutations in the second extracellular domain of PLP1 or in the PLP1-specific region that is spliced out during formation of the DM20 isoform. The authors describe a Korean boy diagnosed with SPG2 caused by a mutation that results in a Pro215Leu substitution in the second extracellular domain. Analysis of phenotypes resulting from mutations affecting PLP1 has been valuable in identifying functional domains of this still incompletely understood major myelin protein. Null mutations and mutations affecting the PLP1-specific domain cause peripheral neuropathy. The PLP1-specific domain also is important in the long-term maintenance of axonal integrity. This patient's phenotype was relatively mild, in contrast with other mutations at position 215 of PLP1 that cause severe PMD. One of these severe mutations is also a missense mutation substituting an aliphatic residue, alanine, for proline. The distinct severity difference between the Pro215Leu and Pro215Ala substitutions suggests that this region of the protein is very sensitive to subtle structural changes and likely plays a critical role in PLP1 function.

    Journal of the neurological sciences 2004;224;1-2;83-7

  • Gene expression profile of the nucleus accumbens of human cocaine abusers: evidence for dysregulation of myelin.

    Albertson DN, Pruetz B, Schmidt CJ, Kuhn DM, Kapatos G and Bannon MJ

    Departments of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.

    Chronic cocaine abuse induces long-term neural adaptations as a consequence of alterations in gene expression. This study was undertaken to identify those transcripts differentially regulated in the nucleus accumbens of human cocaine abusers. Affymetrix microarrays were used to measure transcript abundance in 10 cocaine abusers and 10 control subjects matched for age, race, sex, and brain pH. As expected, gene expression of cocaine- and amphetamine-regulated transcript (CART) was increased in the nucleus accumbens of cocaine abusers. The most robust and consistent finding, however, was a decrease in the expression of a number of myelin-related genes, including myelin basic protein (MBP), proteolipid protein (PLP), and myelin-associated oligodendrocyte basic protein (MOBP). The differential expression seen by microarray for CART as well as MBP, MOBP, and PLP was verified by RT-PCR. In addition, immunohistochemical experiments revealed a decrease in the number of MBP-immunoreactive oligodendrocytes present in the nucleus accumbens and surrounding white matter of cocaine abusers. These findings suggest a dysregulation of myelin in human cocaine abusers.

    Funded by: NIDA NIH HHS: DA06470, DA13753, R01 DA006470, R01 DA013753; NINDS NIH HHS: R01 NS026081-18

    Journal of neurochemistry 2004;88;5;1211-9

  • Complete sequencing and characterization of 21,243 full-length human cDNAs.

    Ota T, Suzuki Y, Nishikawa T, Otsuki T, Sugiyama T, Irie R, Wakamatsu A, Hayashi K, Sato H, Nagai K, Kimura K, Makita H, Sekine M, Obayashi M, Nishi T, Shibahara T, Tanaka T, Ishii S, Yamamoto J, Saito K, Kawai Y, Isono Y, Nakamura Y, Nagahari K, Murakami K, Yasuda T, Iwayanagi T, Wagatsuma M, Shiratori A, Sudo H, Hosoiri T, Kaku Y, Kodaira H, Kondo H, Sugawara M, Takahashi M, Kanda K, Yokoi T, Furuya T, Kikkawa E, Omura Y, Abe K, Kamihara K, Katsuta N, Sato K, Tanikawa M, Yamazaki M, Ninomiya K, Ishibashi T, Yamashita H, Murakawa K, Fujimori K, Tanai H, Kimata M, Watanabe M, Hiraoka S, Chiba Y, Ishida S, Ono Y, Takiguchi S, Watanabe S, Yosida M, Hotuta T, Kusano J, Kanehori K, Takahashi-Fujii A, Hara H, Tanase TO, Nomura Y, Togiya S, Komai F, Hara R, Takeuchi K, Arita M, Imose N, Musashino K, Yuuki H, Oshima A, Sasaki N, Aotsuka S, Yoshikawa Y, Matsunawa H, Ichihara T, Shiohata N, Sano S, Moriya S, Momiyama H, Satoh N, Takami S, Terashima Y, Suzuki O, Nakagawa S, Senoh A, Mizoguchi H, Goto Y, Shimizu F, Wakebe H, Hishigaki H, Watanabe T, Sugiyama A, Takemoto M, Kawakami B, Yamazaki M, Watanabe K, Kumagai A, Itakura S, Fukuzumi Y, Fujimori Y, Komiyama M, Tashiro H, Tanigami A, Fujiwara T, Ono T, Yamada K, Fujii Y, Ozaki K, Hirao M, Ohmori Y, Kawabata A, Hikiji T, Kobatake N, Inagaki H, Ikema Y, Okamoto S, Okitani R, Kawakami T, Noguchi S, Itoh T, Shigeta K, Senba T, Matsumura K, Nakajima Y, Mizuno T, Morinaga M, Sasaki M, Togashi T, Oyama M, Hata H, Watanabe M, Komatsu T, Mizushima-Sugano J, Satoh T, Shirai Y, Takahashi Y, Nakagawa K, Okumura K, Nagase T, Nomura N, Kikuchi H, Masuho Y, Yamashita R, Nakai K, Yada T, Nakamura Y, Ohara O, Isogai T and Sugano S

    Helix Research Institute, 1532-3 Yana, Kisarazu, Chiba 292-0812, Japan.

    As a base for human transcriptome and functional genomics, we created the "full-length long Japan" (FLJ) collection of sequenced human cDNAs. We determined the entire sequence of 21,243 selected clones and found that 14,490 cDNAs (10,897 clusters) were unique to the FLJ collection. About half of them (5,416) seemed to be protein-coding. Of those, 1,999 clusters had not been predicted by computational methods. The distribution of GC content of nonpredicted cDNAs had a peak at approximately 58% compared with a peak at approximately 42%for predicted cDNAs. Thus, there seems to be a slight bias against GC-rich transcripts in current gene prediction procedures. The rest of the cDNAs unique to the FLJ collection (5,481) contained no obvious open reading frames (ORFs) and thus are candidate noncoding RNAs. About one-fourth of them (1,378) showed a clear pattern of splicing. The distribution of GC content of noncoding cDNAs was narrow and had a peak at approximately 42%, relatively low compared with that of protein-coding cDNAs.

    Nature genetics 2004;36;1;40-5

  • Pelizaeus-Merzbacher disease and spastic paraplegia type 2: two faces of myelin loss from mutations in the same gene.

    Hudson LD

    Section of Developmental Genetics, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 36, Room 5D06, 36 Convent Dr, MSC 4160, Bethesda, MD 20892-4160, USA. hudsonl@ninds.nih.gov

    Pelizaeus-Merzbacher disease and X-linked spastic paraplegia type 2 are two sides of the same coin. Both arise from mutations in the gene encoding myelin proteolipid protein. The disease spectrum for Pelizaeus-Merzbacher disease and spastic paraplegia type 2 is extraordinarily broad, ranging from a spastic gait in the pure form of spastic paraplegia type 2 to a severely disabling form of Pelizaeus-Merzbacher disease featuring hypotonia, respiratory distress, stridor, nystagmus, and profound myelin loss. The diverse disease spectrum is mirrored by the underlying pathogenesis, in which a blockade at any stage of myelin proteolipid protein synthesis and assembly into myelin spawns a unique phenotype. The continuing definition of pathogenetic mechanisms operative in Pelizaeus-Merzbacher disease and spastic paraplegia type 2, together with advances in neural cell transplant therapy, augurs well for future treatment of the severe forms of Pelizaeus-Merzbacher disease.

    Journal of child neurology 2003;18;9;616-24

  • Role of calnexin in the glycan-independent quality control of proteolipid protein.

    Swanton E, High S and Woodman P

    School of Biological Sciences, University of Manchester, 2.205 Stopford Building, Oxford Road, Manchester M13 9PT, UK. lisa.swanton@man.ac.uk

    The endoplasmic (ER) quality control apparatus ensures that misfolded or unassembled proteins are not deployed within the cell, but are retained in the ER and degraded. A glycoprotein-specific system involving the ER lectins calnexin and calreticulin is well documented, but very little is known about mechanisms that may operate for non-glycosylated proteins. We have used a folding mutant of a non- glycosylated membrane protein, proteolipid protein (PLP), to examine the quality control of this class of polypeptide. We find that calnexin associates with newly synthesized PLP molecules, binding stably to misfolded PLP. Calnexin also binds stably to an isolated transmembrane domain of PLP, suggesting that this chaperone is able to monitor the folding and assembly of domains within the ER membrane. Notably, this glycan-independent interaction with calnexin significantly retards the degradation of misfolded PLP. We propose that calnexin contributes to the quality control of non-glycosylated polytopic membrane proteins by binding to misfolded or unassembled transmembrane domains, and discuss our findings in relation to the role of calnexin in the degradation of misfolded proteins.

    Funded by: Biotechnology and Biological Sciences Research Council: SF16973

    The EMBO journal 2003;22;12;2948-58

  • Schwann cell expression of PLP1 but not DM20 is necessary to prevent neuropathy.

    Shy ME, Hobson G, Jain M, Boespflug-Tanguy O, Garbern J, Sperle K, Li W, Gow A, Rodriguez D, Bertini E, Mancias P, Krajewski K, Lewis R and Kamholz J

    Department of Neurology and Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA.

    Proteolipid protein (PLP1) and its alternatively spliced isoform, DM20, are the major myelin proteins in the CNS, but are also expressed in the PNS. The proteins have an identical sequence except for 35 amino acids in PLP1 (the PLP1-specific domain) not present in DM20. Mutations of PLP1/DM20 cause Pelizaeus-Merzbacher Disease (PMD), a leukodystrophy, and in some instances, a peripheral neuropathy. To identify which mutations cause neuropathy, we have evaluated a cohort of patients with PMD and PLP1 mutations for the presence of neuropathy. As shown previously, all patients with PLP1 null mutations had peripheral neuropathy. We also identified 4 new PLP1 point mutations that cause both PMD and peripheral neuropathy, three of which truncate PLP1 expression within the PLP1-specific domain, but do not alter DM20. The fourth, a splicing mutation, alters both PLP1 and DM20, and is probably a null mutation. Six PLP1 point mutations predicted to produce proteins with an intact PLP1-specific domain do not cause peripheral neuropathy. Sixty-one individuals with PLP1 duplications also had normal peripheral nerve function. These data demonstrate that expression of PLP1 but not DMSO is necessary to prevent neuropathy, and suggest that the 35 amino acid PLP1-specific domain plays an important role in normal peripheral nerve function.

    Funded by: NINDS NIH HHS: R01 NS043783

    Annals of neurology 2003;53;3;354-65

  • The COS-7 cell in vitro paradigm to study myelin proteolipid protein 1 gene mutations.

    Gow A

    Center for Molecular Medicine and Genetics, Departments of Pediatrics and Neurology, Wayne State University School of Medicine, Detroit, MI, USA.

    Methods in molecular biology (Clifton, N.J.) 2003;217;263-75

  • Myelin proteolipid protein, basic protein, the small isoform of myelin-associated glycoprotein, and p42MAPK are associated in the Triton X-100 extract of central nervous system myelin.

    Arvanitis DN, Yang W and Boggs JM

    Research Institute, The Hospital for Sick Children, Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.

    To further our understanding of the functions of the major myelin proteins, myelin basic protein (MBP) and proteolipid protein (PLP), and other myelin proteins, such as 2'3'-cyclic nucleotide 3'-phosphodiesterase (CNP) and myelin-associated glycoprotein (MAG), bovine brain myelin was extracted with Triton X-100, and protein complexes in the detergent-soluble fraction were isolated by coimmunoprecipitation and sucrose density gradient sedimentation. MBP, PLP, and the small isoform of MAG (S-MAG) were coimmunoprecipitated from the detergent-soluble fraction by anti-PLP, anti-MBP or anti-MAG monoclonal antibodies. Additionally, a 30 kDa phosphoserine-containing protein and two phosphotyrosine-containing proteins (M(r) 30 and 42 kDa) were found in the coimmunoprecipitates. The 42 kDa protein is probably p42MAPK, in that MAPK was shown also to be present in the immunoprecipitated complex. CNP, the small PLP isoform DM20, the large MAG isoform L-MAG, MOG, CD44, MEK, p44MAPK, and actin were not present in the immunoprecipitates, although they were present in the detergent-soluble fraction. Lipid analysis revealed that the PLP-MBP-S-MAG coimmunoprecipitated with some phospholipids and sulfatide but not cholesterol or galactosylceramide. However, the complex had a high density, indicating that the lipid/protein ratio is low, and it was retained on a Sepharose CL6B column, indicating that it is not a large membrane fragment. Given that MAG is localized mainly in the periaxonal region of myelin, where it interacts with axonal ligands, the PLP-MBP-S-MAG complex may come from these regions, where it could participate in dynamic functions in the myelin sheath and myelin-axonal interactions.

    Journal of neuroscience research 2002;70;1;8-23

  • A PLP splicing abnormality is associated with an unusual presentation of PMD.

    Hobson GM, Huang Z, Sperle K, Stabley DL, Marks HG and Cambi F

    Department of Research, Alfred I. duPont Hospital for Children, Wilmington, DE, USA.

    We report that a deletion of 19 base pairs (bp) in intron 3 of the proteolipid protein (PLP/DM20) gene causes a neurological disease characterized by mild developmental delay, followed by progressive decline of acquired motor and cognitive milestones. The clinical features are associated with mild delay in myelination demonstrated by magnetic resonance imaging studies and with ongoing demyelination and axonal loss demonstrated by magnetic resonance spectroscopy. We demonstrate that the purine-rich 19bp element regulates PLP-specific splice site selection in transient transfections of chimeric constructs into cultured oligodendrocytes. Runs of 4 and 5 Gs centered in the 19bp element are critical for efficient PLP-specific splicing. The intronic element is sequence specific in oligodendrocytes and is not a repressor of PLP-specific splicing in nonglial cells. These data support the conclusion that deletion of the 19bp purine-rich region in PLP intron 3 causes a reduction in PLP message and protein, which affects myelin stability and axonal integrity.

    Annals of neurology 2002;52;4;477-88

  • Genomic rearrangements resulting in PLP1 deletion occur by nonhomologous end joining and cause different dysmyelinating phenotypes in males and females.

    Inoue K, Osaka H, Thurston VC, Clarke JT, Yoneyama A, Rosenbarker L, Bird TD, Hodes ME, Shaffer LG and Lupski JR

    Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.

    In the majority of patients with Pelizaeus-Merzbacher disease, duplication of the proteolipid protein gene PLP1 is responsible, whereas deletion of PLP1 is infrequent. Genomic mechanisms for these submicroscopic chromosomal rearrangements remain unknown. We identified three families with PLP1 deletions (including one family described elsewhere) that arose by three distinct processes. In one family, PLP1 deletion resulted from a maternal balanced submicroscopic insertional translocation of the entire PLP1 gene to the telomere of chromosome 19. PLP1 on the 19qtel is probably inactive by virtue of a position effect, because a healthy male sibling carries the same der(19) chromosome along with a normal X chromosome. Genomic mapping of the deleted segments revealed that the deletions are smaller than most of the PLP1 duplications and involve only two other genes. We hypothesize that the deletion is infrequent, because only the smaller deletions can avoid causing either infertility or lethality. Analyses of the DNA sequence flanking the deletion breakpoints revealed Alu-Alu recombination in the family with translocation. In the other two families, no homologous sequence flanking the breakpoints was found, but the distal breakpoints were embedded in novel low-copy repeats, suggesting the potential involvement of genome architecture in stimulating these rearrangements. In one family, junction sequences revealed a complex recombination event. Our data suggest that PLP1 deletions are likely caused by nonhomologous end joining.

    Funded by: NICHD NIH HHS: P01 HD38420, P30 HD024064, P30 HD24064, R01 HD038420; NINDS NIH HHS: R01 NS027042, R01 NS27042

    American journal of human genetics 2002;71;4;838-53

  • Myelin proteolipid protein forms a complex with integrins and may participate in integrin receptor signaling in oligodendrocytes.

    Gudz TI, Schneider TE, Haas TA and Macklin WB

    Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.

    Myelination of axons in the CNS by oligodendrocytes is a process critical to rapid and efficient impulse conduction. A new role for the myelin proteolipid protein (PLP), the most abundant protein of CNS myelin, has been identified, in studies showing PLP interaction with signaling proteins in oligodendrocytes. In particular, these studies suggest that the PLP protein may be involved in signaling through integrins in oligodendrocytes. Stimulation of muscarinic acetylcholine receptors on oligodendrocytes induced formation of a tripartite complex containing PLP, calreticulin, and alpha(v)-integrin. PLP interacted directly with the cytoplasmic domain of the alpha(v)-integrin. Complex formation was mediated by phospholipase C and Ca2+ binding to the high affinity binding site on calreticulin. This complex appears important for binding of fibronectin to oligodendrocytes. These data establish a novel function for PLP as a part of the integrin signaling complex in oligodendrocytes and suggest that neurotransmitter-mediated integrin receptor signaling may be involved in myelinogenesis.

    Funded by: NINDS NIH HHS: NS25304, R01 NS025304

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2002;22;17;7398-407

  • Expressed sequence tag analysis of human RPE/choroid for the NEIBank Project: over 6000 non-redundant transcripts, novel genes and splice variants.

    Wistow G, Bernstein SL, Wyatt MK, Fariss RN, Behal A, Touchman JW, Bouffard G, Smith D and Peterson K

    Section on Molecular Structure and Function, National Eye Institute, National Institutes of Health, Bethesda, MD 20892-2740, USA. graeme@helix.nih.gov

    Purpose: The retinal pigment epithelium (RPE) and choroid comprise a functional unit of the eye that is essential to normal retinal health and function. Here we describe expressed sequence tag (EST) analysis of human RPE/choroid as part of a project for ocular bioinformatics.

    Methods: A cDNA library (cs) was made from human RPE/choroid and sequenced. Data were analyzed and assembled using the program GRIST (GRouping and Identification of Sequence Tags). Complete sequencing, Northern and Western blots, RH mapping, peptide antibody synthesis and immunofluorescence (IF) have been used to examine expression patterns and genome location for selected transcripts and proteins.

    Results: Ten thousand individual sequence reads yield over 6300 unique gene clusters of which almost half have no matches with named genes. One of the most abundant transcripts is from a gene (named "alpha") that maps to the BBS1 region of chromosome 11. A number of tissue preferred transcripts are common to both RPE/choroid and iris. These include oculoglycan/opticin, for which an alternative splice form is detected in RPE/choroid, and "oculospanin" (Ocsp), a novel tetraspanin that maps to chromosome 17q. Antiserum to Ocsp detects expression in RPE, iris, ciliary body, and retinal ganglion cells by IF. A newly identified gene for a zinc-finger protein (TIRC) maps to 19q13.4. Variant transcripts of several genes were also detected. Most notably, the predominant form of Bestrophin represented in cs contains a longer open reading frame as a result of splice junction skipping.

    Conclusions: The unamplified cs library gives a view of the transcriptional repertoire of the adult RPE/choroid. A large number of potentially novel genes and splice forms and candidates for genetic diseases are revealed. Clones from this collection are being included in a large, nonredundant set for cDNA microarray construction.

    Molecular vision 2002;8;205-20

  • Patients lacking the major CNS myelin protein, proteolipid protein 1, develop length-dependent axonal degeneration in the absence of demyelination and inflammation.

    Garbern JY, Yool DA, Moore GJ, Wilds IB, Faulk MW, Klugmann M, Nave KA, Sistermans EA, van der Knaap MS, Bird TD, Shy ME, Kamholz JA and Griffiths IR

    Department of Neurology and Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, USA. jgarbern@med.wayne.edu

    Axonal degeneration contributes to clinical disability in the acquired demyelinating disease multiple sclerosis. Axonal degeneration occurs during acute attacks, associated with inflammation, and during the chronic progressive phase of the disease in which inflammation is not prominent. To explore the importance of interactions between oligodendrocytes and axons in the CNS, we analysed the brains of rodents and humans with a null mutation in the gene encoding the major CNS myelin protein, proteolipid protein (PLP1, previously PLP). Histological analyses of the CNS of Plp1 null mice and of autopsy material from patients with null PLP1 mutations were performed to evaluate axonal and myelin integrity. In vivo proton magnetic resonance spectroscopy (MRS) of PLP1 null patients was conducted to measure levels of N-acetyl aspartate (NAA), a marker of axonal integrity. Length-dependent axonal degeneration without demyelination was identified in the CNS of Plp1 null mice. Proton MRS of PLP1-deficient patients showed reduced NAA levels, consistent with axonal loss. Analysis of patients' brain tissue also demonstrated a length-dependent pattern of axonal loss without significant demyelination. Therefore, axonal degeneration occurs in humans as well as mice lacking the major myelin protein PLP1. This degeneration is length-dependent, similar to that found in the PNS of patients with the inherited demyelinating neuropathy, CMT1A, but is not associated with significant demyelination. Disruption of PLP1-mediated axonal--glial interactions thus probably causes this axonal degeneration. A similar mechanism may be responsible for axonal degeneration and clinical disability that occur in patients with multiple sclerosis.

    Brain : a journal of neurology 2002;125;Pt 3;551-61

  • Genotype-phenotype correlation in inherited brain myelination defects due to proteolipid protein gene mutations. Clinical European Network on Brain Dysmyelinating Disease.

    Cailloux F, Gauthier-Barichard F, Mimault C, Isabelle V, Courtois V, Giraud G, Dastugue B and Boespflug-Tanguy O

    INSERM U384, Faculté de Médecine, Clermont-Ferrand, France.

    Pelizaeus-Merzbacher disease (PMD) and spastic paraplegia type 2 (SPG2) are X-linked developmental defects of myelin formation affecting the central nervous system (CNS). They differ clinically in the onset and severity of the motor disability but both are allelic to the proteolipid protein gene (PLP), which encodes the principal protein components of CNS myelin, PLP and its spliced isoform, DM20. We investigated 52 PMD and 28 SPG families without large PLP duplications or deletions by genomic PCR amplification and sequencing of the PLP gene. We identified 29 and 4 abnormalities respectively. Patients with PLP mutations presented a large range of disease severity, with a continuum between severe forms of PMD, without motor development, to pure forms of SPG. Clinical severity was found to be correlated with the nature of the mutation, suggesting a distinct strategy for detection of PLP point mutations between severe PMD, mild PMD and SPG. Single amino-acid changes in highly conserved regions of the DM20 protein caused the most severe forms of PMD. Substitutions of less conserved amino acids, truncations, absence of the protein and PLP-specific mutations caused the milder forms of PMD and SPG. Therefore, the interactions and stability of the mutated proteins has a major effect on the severity of PLP-related diseases.

    European journal of human genetics : EJHG 2000;8;11;837-45

  • The proteolipid protein gene and myelin disorders in man and animal models.

    Yool DA, Edgar JM, Montague P and Malcolm S

    Applied Neurobiology Group, Glasgow University Veterinary School, Bearsden Road, Glasgow G61 1QH, UK. d.yool@vet.gla.ac.uk

    The two proteins, proteolipid protein and DM20, which are encoded by alternative transcripts from the proteolipid protein ( PLP ) gene, are major components of central nervous system myelin. In man, mutations of these proteins cause Pelizaeus-Merzbacher disease (PMD), an X-linked dysmyelinating neuropathy. The mutations found are very varied, ranging from deletions, loss-of-function and missense mutations to additional copies of the gene. This same range of known genetic defects has been observed in animal models with spontaneous and engineered Plp gene mutations. The relationship between genotype and phenotype is remarkably close in the animal models and the PMD cases, making them useful models for studying the mechanisms of PLP gene-related disease. As a result, it has become clear that the PLP gene plays a wider role in neural development in addition to its function as a structural component of myelin. It has also emerged that duplications of the PLP gene are the commonest mutation in PMD. Genetic disorders arising from a dosage effect may be more common than previously recognized. The study of the PLP gene in this rare disorder is, therefore, contributing both to our understanding of neural development and maintenance and to the mechanisms of human genetic disorders.

    Human molecular genetics 2000;9;6;987-92

  • The molecular pathogenesis of Pelizaeus-Merzbacher disease.

    Garbern J, Cambi F, Shy M and Kamholz J

    Department of Neurology, Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Mich, USA.

    In 1885, Pelizaeus described 5 boys in a single family with nystagmus, spastic quadriparesis, ataxia, and delay in cognitive development. In 1910, Merzbacher reexamined this family, which then included 14 affected individuals, including 2 girls, and found that all affected family members shared a common female ancestor. Also, he noted that the disease was passed exclusively through the female line without male-to-male transmission. Pathological analysis of brain tissue from one affected individual showed that most of the central white matter lacked histochemical staining for myelin, although there were occasional small regions of preserved myelin, giving the sections a "tigroid" appearance. The description of this family provides the clinical, genetic, and pathological basis for Pelizaeus-Merzbacher disease (PMD): an X-linked disorder of myelination classically characterized by nystagmus, spastic quadriparesis, ataxia, and cognitive delay in early childhood.

    Archives of neurology 1999;56;10;1210-4

  • Proteolipoprotein gene analysis in 82 patients with sporadic Pelizaeus-Merzbacher Disease: duplications, the major cause of the disease, originate more frequently in male germ cells, but point mutations do not. The Clinical European Network on Brain Dysmyelinating Disease.

    Mimault C, Giraud G, Courtois V, Cailloux F, Boire JY, Dastugue B and Boespflug-Tanguy O

    INSERM U.384-Faculté de Médecine, Clermont-Ferrand Cedex, France.

    Pelizaeus-Merzbacher Disease (PMD) is an X-linked developmental defect of myelination affecting the central nervous system and segregating with the proteolipoprotein (PLP) locus. Investigating 82 strictly selected sporadic cases of PMD, we found PLP mutations in 77%; complete PLP-gene duplications were the most frequent abnormality (62%), whereas point mutations in coding or splice-site regions of the gene were involved less frequently (38%). We analyzed the maternal status of 56 cases to determine the origin of both types of PLP mutation, since this is relevant to genetic counseling. In the 22 point mutations, 68% of mothers were heterozygous for the mutation, a value identical to the two-thirds of carrier mothers that would be expected if there were an equal mutation rate in male and female germ cells. In sharp contrast, among the 34 duplicated cases, 91% of mothers were carriers, a value significantly (chi2=9. 20, P<.01) in favor of a male bias, with an estimation of the male/female mutation frequency (k) of 9.3. Moreover, we observed the occurrence of de novo mutations between parental and grandparental generations in 17 three-generation families, which allowed a direct estimation of the k value (k=11). Again, a significant male mutation imbalance was observed only for the duplications. The mechanism responsible for this strong male bias in the duplications may involve an unequal sister chromatid exchange, since two deletion events, responsible for mild clinical manifestations, have been reported in PLP-related diseases.

    American journal of human genetics 1999;65;2;360-9

  • Novel exon 3B proteolipid protein gene mutation causing late-onset spastic paraplegia type 2 with variable penetrance in female family members.

    Sivakumar K, Sambuughin N, Selenge B, Nagle JW, Baasanjav D, Hudson LD and Goldfarb LG

    Medical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-1361, USA.

    Spastic paraplegia type 2 (SPG2) is allelic to Pelizaeus-Merzbacher disease (PMD), with both conditions resulting from mutations in the proteolipid protein gene (PLP). We report an SPG2 family in which 3 male members and a heterozygous female member were affected with spastic paraplegia characterized by relatively late onset and mild clinical manifestations. A unique H147Y mutation in exon 3B of the PLP altering the proteolipid protein (PLP) but not the alternatively spliced DM20 isoform was identified as the cause of this distinct disease phenotype. Cellular pathology studies of SPG2 mutations offer an explanation for the paradoxical finding that mutations associated with the mildest phenotype in male family members also affect female carriers.

    Annals of neurology 1999;45;5;680-3

  • Proteolipid protein gene: Pelizaeus-Merzbacher disease in humans and neurodegeneration in mice.

    Woodward K and Malcolm S

    Molecular Genetics Unit, Institute of Child Health, 30 Guilford Street, London, UK WC1N 1EH. kwoodwar@hgmp.mrc.ac.uk

    The dosage of the myelin gene and mutant forms of the protein can affect the CNS and PNS. Pelizaeus-Merzbacher disease (PMD) is a myelin disorder of the CNS that arises from both mutational mechanisms. Investigating the molecular basis of PMD in patients and animal models is furthering our understanding of the disease, dosage sensitivity and proteolipid protein function during myelinogenesis.

    Funded by: Wellcome Trust

    Trends in genetics : TIG 1999;15;4;125-8

  • Different mutations in the same codon of the proteolipid protein gene, PLP, may help in correlating genotype with phenotype in Pelizaeus-Merzbacher disease/X-linked spastic paraplegia (PMD/SPG2).

    Hodes ME, Zimmerman AW, Aydanian A, Naidu S, Miller NR, Garcia Oller JL, Barker B, Aleck KA, Hurley TD and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA. mhodes@medgen.iupui.edu

    Pelizaeus-Merzbacher disease/X-linked spastic paraplegia (PMD/SPG2) comprises a spectrum of diseases that range from severe to quite mild. The reasons for the variation in severity are not obvious, but suggested explanations include the extent of disruption of the transmembrane portion of the proteolipid protein caused by certain amino acid substitutions and interference with the trafficking of the PLP molecule in oligodendrocytes. Four codons in which substitution of more than one amino acid has occurred are available for examination of clinical and potential structural manifestations: Valine165 to either glutamate or glycine, leucine 045 to either proline or arginine, aspartate 202 to asparagine or histidine, and leucine 223 to isoleucine or proline. Three of these mutations, Val165Gly, Leu045Pro, and Leu223Ile have not been described previously in humans. The altered amino acids appear in the A-B loop, C helix, and C-D loop, respectively. We describe clinically patients with the mutations T494G (Val165Gly), T134C (Leu045Pro), and C667A (Leu223Ile). We discuss also the previously reported mutations Asp202Asn and Asp202His. We have calculated the changes in hydrophobicity of short sequences surrounding some of these amino acids and compared the probable results of the changes in transmembrane structure of the proteolipid protein for the various mutations with the clinical data available on the patients. While the Val165Glu mutation, which is expected to produce disruption of a transmembrane loop of the protein, produces more severe disease than does Val165Gly, no particular correlation with hydrophobicity is found for the other mutations. As these are not in transmembrane domains, other factors such as intracellular transport or interaction between protein chains during myelin formation are probably at work.

    American journal of medical genetics 1999;82;2;132-9

  • Pelizaeus-Merzbacher disease: three novel mutations and implication for locus heterogeneity.

    Osaka H, Kawanishi C, Inoue K, Onishi H, Kobayashi T, Sugiyama N, Kosaka K, Nezu A, Fujii K, Sugita K, Kodama K, Murayama K, Murayama S, Kanazawa I and Kimura S

    Department of Pediatrics, School of Medicine, Yokohama City University, Yokohama, Japan.

    We report a mutational and polymorphic analysis of the proteolipid protein gene in members of 27 Japanese families with Pelizaeus-Merzbacher disease. We found causative mutations in 6 members of 27 families (22.2%); 5 of the 6 mutations, including two novel mutations, Leu45Arg and 231 + 2T --> G, resulted in the typically severe clinical symptoms. Paradoxically, the Cys219Tyr mutation, presumed to disrupt the tertiary structure of proteolipid protein by removing the disulfide bond between Cys200 and Cys219, was associated with a mild clinical presentation wherein the patient could walk with assistance and speak. It was inferred that the structural change prevented the toxicity associated with a gain of function mutation. Moreover, in one family 3 patients exhibited a intragenic polymorphism that did not segregate with the disease, suggesting a locus heterogeneity for Pelizaeus-Merzbacher disease.

    Annals of neurology 1999;45;1;59-64

  • Human proteolipid protein (PLP) mediates winding and adhesion of phospholipid membranes but prevents their fusion.

    Palaniyar N, Semotok JL, Wood DD, Moscarello MA and Harauz G

    Department of Molecular Biology and Genetics, The University of Guelph, 50 Stone Road East, Guelph, Ont. N1G 2W1, Canada.

    Proteolipid protein (PLP or lipophilin) is a highly conserved, strongly hydrophobic, integral membrane protein, and is the major protein component of central nervous system myelin. Although PLP has been implicated in many functions, its in vivo role is still uncertain. Here, we report the investigation of PLP's putative adhesive function using purified PLP and reconstituted phospholipid vesicles made of either 100% phosphatidylcholine (PC), or a mixture of 92% PC and 8% phosphatidylserine (PS), by weight. PLP-induced changes in the phospholipid bilayer surfaces were directly examined by transmission electron microscopy. We found that upon the introduction of PLP, larger lipid vesicles became smaller and unilamellar. At the PLP:lipid molar ratio of 1:20, vesicle membranes rolled onto themselves forming 'croissant'-like structures that subsequently adhered to each other. The phenomena of PLP-induced bilayer rolling and adhesion were dependent on the concentration of PLP and the period of incubation, but were independent of the presence of calcium and types of phospholipids (PC or PC:PS). Furthermore, the presence of PLP in the lipid bilayers prevented the fusion of membranes. These findings show that PLP can induce membrane 'winding' while preventing the fusion of adjacent lipid bilayers. Hence, our data provide direct evidence for PLP's suspected function of membrane adhesion, and also suggest that PLP could potentially play a role in the formation of the myelin sheath.

    Biochimica et biophysica acta 1998;1415;1;85-100

  • Cotranslational integration of myelin proteolipid protein (PLP) into the membrane of endoplasmic reticulum: analysis of topology by glycosylation scanning and protease domain protection assay.

    Wahle S and Stoffel W

    Institute of Biochemistry, Faculty of Medicine, University of Cologne, Germany.

    The four transmembrane domain topology of the proteolipid protein (PLP) in the myelin membrane of the central nervous system (CNS) has been further substantiated by biochemical studies. We have analyzed the cotranslational polytopic integration of nascent PLP during protein synthesis into the membrane of the endoplasmic reticulum (ER) on two routes. Consensus sequences for N-glycosylation were introduced by site directed mutagenesis into the PLP sequence as reporter sites, which upon glycosylation monitor the intraluminal location of the respective domains corresponding to the extracellular side of the plasma membrane. Single, double, and triple mutant cDNAs were constructed for transcription/translation in vitro in the presence of ER-membranes. The glycosylation pattern of the translation products revealed that hydrophilic extramembrane regions 2 and 4 (EMR2/EMR4) and EMR3 of PLP are exposed on opposite sides of the ER membrane. Their localization either at the cytosolic or luminal side of the ER membrane leads to two different topologies. The two modes of membrane integration during in vitro cotranslational translocation were confirmed by protease protection assays with wild-type and truncated PLP polypeptides with either one, two, or three putative transmembrane domains integrated into the ER-membrane. The fragment pattern of the [35S]methionine- or [3H]leucine-labeled polypeptides revealed that EMR3 and EMR4 were exposed with opposite orientation either on the cytosolic or luminal side of the ER membrane supporting the 4-transmembrane helix (TMH) N(in) model with the N and C termini on the cytoplasmic side, as established for the myelin membrane (plasma membrane); the other inversely integrated PLP constructs indicate the 4-TMH-Nout profile. These results are discussed with regard to the PLP biogenesis and the plasma membrane topology in PLP-expressing cells.

    Glia 1998;24;2;226-35

  • A de novo mutation (C755T; Ser252Phe) in exon 6 of the proteolipid protein gene responsible for Pelizaeus-Merzbacher disease.

    Hodes ME, Aydanian A, Dlouhy SR, Whelan DT, Heshka T and Ronen G

    Clinical genetics 1998;54;3;248-9

  • Duplication of the proteolipid protein gene is the major cause of Pelizaeus-Merzbacher disease.

    Sistermans EA, de Coo RF, De Wijs IJ and Van Oost BA

    Department of Human Genetics, University Hospital Nijmegen, The Netherlands.

    Pelizaeus-Merzbacher disease (PMD), an X-linked recessive dysmyelination disorder, is caused by mutations in the proteolipid protein (PLP) gene. However, missense mutations were only found in a fraction of PMD patients, even in families that showed linkage with the PLP locus on Xq22. Here we describe the use of an extended protocol that includes screening for both missense mutations and duplications.

    Method: Two groups of patients were analyzed, one group with 10 independent PMD families and one group with 24 sporadic patients suspected of PMD. Missense mutations in the PLP gene were identified by sequencing. PLP gene duplications were detected by quantitative polymerase chain reaction and/or Southern blot analysis.

    Results: Sequencing of the PLP gene revealed four mutations in group 1 and one mutation in group 2. However, inclusion of duplication analysis in the screening protocol raised the amount of mutations found in group 1 from 40 to 90%, and in group 2 from 4 to 25%.

    Conclusions: These results demonstrate that duplications of the PLP gene are the major cause of PMD. Furthermore, it appears that the phenotype resulting from PLP duplications is relatively mild, and that many probands are nontypical PMD patients.

    Neurology 1998;50;6;1749-54

  • X-linked spastic paraplegia due to a mutation (C506T; Ser169Phe) in exon 4 of the proteolipid protein gene (PLP).

    Hodes ME, Hadjisavvas A, Butler IJ, Aydanian A and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA. mhodes@medgen.iupui.edu

    A transition C506T was found in exon 4 of the proteolipid protein gene of a boy with spastic paraplegia. This mutation resulted in the substitution of phenylalanine for serine 169, which is in the third transmembrane domain of the proteolipid protein molecule. The mutation apparently arose de novo, as it was absent from his mother.

    American journal of medical genetics 1998;75;5;516-7

  • Connatal Pelizaeus-Merzbacher disease: a missense mutation in exon 4 of the proteolipid protein (PLP) gene.

    Nagao M and Kadowaki J

    Department of Pediatrics, National Otaru Hospital, Hokkaido, Japan. CXQ04341@niftyserve.or.jp

    We investigated the proteolipid protein (PLP) gene in two brothers in a Japanese family with a connatal form of Pelizaeus-Merzbacher disease (PMD). Direct sequencing of the PLP gene revealed an A-to-T transition in exon 4, which led to an Asp-to-Val substitution at residue 202. Their mother was confirmed to be heterozygous for the mutation. The mutation was not found in 78 X-chromosomes of normal Japanese individuals. A correlation between the clinical severity of the disease in the brothers and the Asp202-to-Val mutation in the PLP gene was suggested.

    Journal of human genetics 1998;43;3;206-8

  • Proteolipid protein is necessary in peripheral as well as central myelin.

    Garbern JY, Cambi F, Tang XM, Sima AA, Vallat JM, Bosch EP, Lewis R, Shy M, Sohi J, Kraft G, Chen KL, Joshi I, Leonard DG, Johnson W, Raskind W, Dlouhy SR, Pratt V, Hodes ME, Bird T and Kamholz J

    Department of Neurology, Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.

    Alternative products of the proteolipid protein gene (PLP), proteolipid protein (PLP) and DM20, are major components of compact myelin in the central nervous system, but quantitatively minor constituents of Schwann cells. A family with a null allele of PLP has a less severe CNS phenotype than those with other types of PLP mutations. Moreover, individuals with PLP null mutations have a demyelinating peripheral neuropathy, not seen with other PLP mutations of humans or animals. Direct analysis of normal peripheral nerve demonstrates that PLP is localized to compact myelin. This and the clinical and pathologic observations of the PLP null phenotype indicate that PLP/DM20 is necessary for proper myelin function both in the central and peripheral nervous systems.

    Neuron 1997;19;1;205-18

  • Mutations in the proteolipid protein gene in Japanese families with Pelizaeus-Merzbacher disease.

    Inoue K, Osaka H, Kawanishi C, Sugiyama N, Ishii M, Sugita K, Yamada Y and Kosaka K

    Department of Psychiatry, Yokohama City University, School of Medicine, Japan.

    Pelizaeus-Merzbacher disease (PMD) is a rare X-linked dysmyelinating disorder of the CNS resulting from abnormalities in the proteolipid protein (PLP) gene. Exonic mutations in the PLP gene are present in 10 to 25% of all cases. In investigating genotype-phenotype correlations, we screened five Japanese families with PMD for PLP gene mutations and compared their clinical manifestations. We identified two novel nucleotide substitutions in exon 5, at V208N and at P210L, in two families. In the remaining three families, there were no mutations detected. Although all patients satisfied the criteria for the classical form of PMD, two families not carrying the mutations showed milder clinical manifestations than those with the mutations. Since linkage analysis has shown homogeneity at the PLP locus in patients with PMD, our findings suggest that there may be genetic abnormalities other than exonic mutations that cause milder forms of PMD.

    Neurology 1997;48;1;283-5

  • A new missense mutation in exon 6 of the proteolipid protein gene in a patient with Pelizaeus-Merzbacher disease.

    Kawanishi C, Osaka H, Owa K, Inoue K, Miyakawa T, Onishi H, Yamada Y, Suzuki K, Kimura S and Kosaka K

    Department of Psychiatry, Yokohama City University, Japan.

    Human mutation 1997;9;5;475-6

  • Adult-onset neurodegenerative disorder due to proteolipid protein gene mutation in the mother of a man with Pelizaeus-Merzbacher disease.

    Nance MA, Boyadjiev S, Pratt VM, Taylor S, Hodes ME and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA.

    A 23-year-old man with Pelizaeus-Merzbacher disease had a novel mutation, C344A (Thr115Lys), in exon 3 of the proteolipid protein gene (PLP) His mother, heterozygous for the mutation, developed progressive personality change and a gait disorder in her mid-20s. Her MRI at age 53 showed a diffuse severe leukodystrophy. This report extends the phenotypic range of disease due to PLP gene mutations to include adult-onset dementia in females.

    Neurology 1996;47;5;1333-5

  • A cellular mechanism governing the severity of Pelizaeus-Merzbacher disease.

    Gow A and Lazzarini RA

    Brookdale Center for Molecular Biology, Mount Sinai School of Medicine, New York, New York 10029-6574, USA.

    Pelizaeus-Merzbacher disease (PMD) is a leukodystrophy linked to the proteolipid protein gene (PLP). We report a cellular basis for the distinction between two disease subtypes, classical and connatal, based on protein trafficking of the two PLP gene products (PLP and DM20). Classical PMD mutations correlate with accumulation of PLP in the ER of transfected COS-7 cells while the cognate DM20 traverses the secretory pathway to the cell surface. On the other hand, connatal PMD mutations lead to the accumulation of both mutant PLP and DM20 proteins in the ER of COS-7 cells with little of either isoform transported to the cell surface. Moreover, we show that transport-competent mutant DM20s facilitate trafficking of cognate PLPs and hence may influence disease severity.

    Funded by: NINDS NIH HHS: 3P01NS33165-01A1S1

    Nature genetics 1996;13;4;422-8

  • Expression of the myelin proteolipid protein gene in the human fetal thymus.

    Pribyl TM, Campagnoni CW, Kampf K, Kashima T, Handley VW, McMahon J and Campagnoni AT

    Mental Retardation Research Center, U.C.L.A. School of Medicine 90095, USA.

    We have analyzed human fetal thymus and spleen for expression of the proteolipid protein (PLP) gene. We demonstrate that the PLP gene is transcribed in both tissues, and that both the PLP and DM-20 mRNAs are produced. Western blot analyses revealed that both the PLP and DM-20 protein isoforms were present in the fetal thymus and spleen. Immunohistochemical analyses indicated that the PLP/DM-20 proteins were detected in cells which have the distribution and morphology of thymic macrophages. These results provide further evidence that the PLP and DM-20 proteins are expressed in cell types other than myelin forming cells and possess function(s) unrelated to myelin structure. Furthermore, these data demonstrate that the PLP and DM-20 proteins are not shielded from the immune system behind the blood-brain barrier. These observations directly impinge upon the debate concerning acquisition of tolerance and the recognition that the encephalitogenic nature of PLP in diseases, such as Multiple Sclerosis, may not simply be related to its 'sequestration' from a 'naive' immune system.

    Funded by: NINDS NIH HHS: NS23022, NS23322

    Journal of neuroimmunology 1996;67;2;125-30

  • Refined genetic mapping and proteolipid protein mutation analysis in X-linked pure hereditary spastic paraplegia.

    Cambi F, Tang XM, Cordray P, Fain PR, Keppen LD and Barker DF

    Department of Neurology, Thomas Jefferson University, Philadelphia, PA, USA.

    X-linked hereditary spastic paraplegias (HSP) present with two distinct phenotypes, pure and complicated. The pure form is characterized by spasticity and gait difficulties but lacks the additional features (nystagmus, dysarthria, mental retardation) present in the complicated form. The complicated form is heterogeneous, caused by mutations of the L1CAM gene at Xq28 (SPG1) or the PLP gene at Xq22 (SPG2) that is allelic to Pelizaeus-Merzbacher disease (PMD). Since in one kindred (K313) the pure form of HSP was also mapped to Xq22, this raises the issue as to whether a pure form of HSP exists that is allelic to X-linked complicated HSP (SPG2) and PMD. To answer this question, we carried out linkage analysis in a new pedigree with pure HSP (K101) and refined linkage in pedigree K313. The PLP gene was also screened for mutation by direct sequencing and reverse-transcriptase polymerase chain reaction (RT-PCR). In both families, the disease locus mapped to Xq22 with Lod scores at zero recombination of 5.3 for COL4A5 2B6 in K313 and 2.4 for DXS101 in K101. A T to C transition in exon 5 of the PLP gene was identified from affected individuals of K313. This transition causes a Ser to Pro mutation in the major extracellular loop of PLP/DM20. This finding demonstrates that a form of X-linked pure spastic paraplegia, X-linked complicated HSP (SPG2) and PMD are allelic disorders. There was no evidence of mutations in either coding sequences or the intron/exon junctions of PLP in pedigree K101, suggesting that the disease-producing mutation may be in the noncoding portions of PLP or in a nearby gene.

    Funded by: NINDS NIH HHS: NS01726-02

    Neurology 1996;46;4;1112-7

  • A novel mutation in exon 6 (F236S) of the proteolipid protein gene is associated with spastic paraplegia.

    Donnelly A, Colley A, Crimmins D and Mulley J

    Centre for Medical Genetics, Department of Cytogenetics and Molecular Genetics, Women's and Children's Hospital, Adelaide, South Australia.

    Human mutation 1996;8;4;384-5

  • Pelizaeus-Merzbacher disease caused by a de novo mutation that originated in exon 2 of the maternal great-grandfather of the propositus.

    Pratt VM, Boyadjiev S, Green K, Hodes ME and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA.

    Pelizaeus-Merzbacher disease (PMD) is an X-linked dysmyelinating disorder of the central nervous system. Many cases of PMD can be attributed to defects in the proteolipid protein gene (PLP). To date, with one exception, each family has had either no or a unique mutation in one of the seven exons of PLP. We describe a new missense mutation in exon 2 of the PLP gene of an affected individual. This mutation codes for Ile instead of Thr at codon 42. The point mutation originated in the X chromosome of the maternal great-grandfather of the propositus. This was determined from the pattern of inheritance of the AhaII polymorphism and a series of microsatellite markers that are localized near PLP at Xq22.

    American journal of medical genetics 1995;58;1;70-3

  • In-frame deletion in the proteolipid protein gene of a family with Pelizaeus-Merzbacher disease.

    Kleindorfer DO, Dlouhy SR, Pratt VM, Jones MC, Trofatter JA and Hodes ME

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251, USA.

    We describe an in-frame deletion of parts of exons 3 and 4 of the proteolipid protein gene (PLP), with all of the intervening sequence, in a 3-generation family with Pelizaeus-Merzbacher disease. The mutation removes 49 amino acids of the PLP.

    American journal of medical genetics 1995;55;4;405-7

  • A novel mutation in exon 3 of the proteolipid protein gene in Pelizaeus-Merzbacher disease.

    Pratt VM, Naidu S, Dlouhy SR, Marks HG and Hodes ME

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis.

    Neurology 1995;45;2;394-5

  • Pelizaeus-Merzbacher disease: a point mutation in exon 6 of the proteolipid protein (PLP) gene.

    Pratt VM, Dlouhy SR and Hodes ME

    Pelizaeus-Merzbacher disease has been known since 1885. It is characterized by severe dysmyelination of the central nervous system. We describe a new mutation in exon 6 of the proteolipid protein gene in a 9-year-old boy with severe connatal Pelizaeus-Merzbacher disease.

    Clinical genetics 1995;47;2;99-100

  • The rumpshaker mutation in spastic paraplegia.

    Kobayashi H, Hoffman EP and Marks HG

    Funded by: NINDS NIH HHS: NS 28403

    Nature genetics 1994;7;3;351-2

  • X-linked spastic paraplegia and Pelizaeus-Merzbacher disease are allelic disorders at the proteolipid protein locus.

    Saugier-Veber P, Munnich A, Bonneau D, Rozet JM, Le Merrer M, Gil R and Boespflug-Tanguy O

    Service de Génétique, Unité de Recherches sur les Handicaps Génétiques de l'Enfant, INSERM U.393 Paris, France.

    Three forms of X-linked spastic paraplegia (SPG) have been defined. One locus (SPG 1) maps to Xq28 while two clinically distinct forms map to Xq22 (SPG2). A rare X-linked dysmyelinating disorder of the central nervous system, Pelizaeus-Merzbacher disease (PMD), has also been mapped to Xq21-q22, and is caused by mutations in the proteolipid protein gene (PLP) which encodes two myelin proteins, PLP and DM20. While narrowing the genetic interval containing SPG2 in a large pedigree, we found that PLP was the closest marker to the disease locus, implicating PLP as a possible candidate gene. We have found that a point mutation (His139Tyr) in exon 3B of an affected male produces a mutant PLP but a normal DM20, and segregates with the disease (Zmax = 6.63, theta = 0.00). It appears, therefore, that SPG2 and PMD are allelic disorders.

    Nature genetics 1994;6;3;257-62

  • Linkage of a new mutation in the proteolipid protein (PLP) gene to Pelizaeus-Merzbacher disease (PMD) in a large Finnish kindred.

    Pratt VM, Kiefer JR, Lähdetie J, Schleutker J, Hodes ME and Dlouhy SR

    Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis 46202-5251.

    The purpose of this study was to confirm linkage of the proteolipid protein gene (PLP) and Pelizaeus-Merzbacher disease (PMD). A T-->A transversion in nucleotide pair 35 of exon 4 of PLP was found in a large Finnish kindred with PMD. This mutation results in the substitution Val165-->Glu165. We used a combination of single-strand conformational polymorphism and PCR primer extension to determine the presence or absence of the point mutation in family members. A lod score of 2.6 (theta = 0) was found for linkage of the gene and the disease. We examined 101 unrelated X chromosomes and found none with the transversion. This is the second report of linkage of PMD to a missense mutation in PLP. These findings support the hypothesis that PMD in this family is a result of the missense mutation present in exon 4 of PLP.

    American journal of human genetics 1993;52;6;1053-6

  • Pelizaeus-Merzbacher disease: a frameshift deletion/insertion event in the myelin proteolipid gene.

    Pham-Dinh D, Boespflug-Tanguy O, Mimault C, Cavagna A, Giraud G, Leberre G, Lemarec B and Dautigny A

    Equipe ATIPE, URA 1488 CNRS, Paris, France.

    Among the central nervous system (CNS) dysmyelinating disorders, Pelizaeus-Merzbacher disease (PMD) has been individualized by its X-linked mode of inheritance and the existence of corresponding animal models. Mutations in the major myelin proteolipid (PLP) gene coding for PLP and its splicing variant DM20 protein, have been demonstrated in animal mutants and more recently in PMD affected patients. We have identified, in a two-generation PMD affected family, an insertion/deletion event in the exon IV of the PLP gene, leading to the synthesis of predicted truncated PLP and DM20 proteins with altered carboxyl terminal end. This is the first report of a frameshift mutation in the PLP gene in PMD.

    Human molecular genetics 1993;2;4;465-7

  • A missense mutation in the proteolipid protein gene responsible for Pelizaeus-Merzbacher disease in a Japanese family.

    Iwaki A, Muramoto T, Iwaki I, Furumi H, Dario-deLeon ML, Tateishi J and Fukumaki Y

    Research Laboratory for Genetic Information, Kyushu University, Fukuoka, Japan.

    We investigated the proteolipid protein (PLP) gene of two boys in a Japanese family with Pelizaeus-Merzbacher disease (PMD), an X-linked neurologic disorder characterized by dysmyelination in the central nervous system (CNS). The patients showed similar clinical signs from birth and autopsy on the elder brother confirmed a connatal type of PMD. Direct sequencing of the PLP gene and PLP mRNAs from the brain of the PMD patient revealed a G to T transition in exon V of the PLP gene, which leads to a glycine to cysteine substitution at residue 220. Allele-specific oligonucleotide hybridization revealed that this mutation was also present in his brother, but was absent in 100 X chromosomes of normal Japanese individuals. Northern blot analysis showed that the mRNA levels of PLP and myelin basic protein, two major myelin proteins produced by oligodendrocytes, were much reduced in the PMD brain, hence, there was a specific loss of oligodendrocytes. It seems likely that the substitution is responsible for PMD (connatal type) in this particular family and causes oligodendrocytes death in the CNS.

    Human molecular genetics 1993;2;1;19-22

  • A novel mutation in the proteolipid protein gene leading to Pelizaeus-Merzbacher disease.

    Otterbach B, Stoffel W and Ramaekers V

    Institut für Biochemie, Medizinische Fakultät, Universität Köln.

    Point mutations of the gene of human proteolipid protein (PLP) have been recognized as the molecular basis of one form of leukodystrophy, the X-chromosome-linked Pelizaeus-Merzbacher disease (PMD). We report the molecular analysis of four PMD patients in three unrelated families and describe a point mutation (G-->A transition) in exon V which leads to the substitution of Gly216 by a serine residue in a highly conserved extracytosolic domain and a Mae I RFLP. Molecular modelling with energy minimization indicates that this seemingly minor alteration of the amino-acid sequence induces a considerable conformational change and tight packing of the polypeptide chain apparently not compatible with the regular PLP function in oligodendrocytes. This mutation has been detected and characterized by PCR amplification of genomic DNA using intron and exon primers and the complete sequence analysis of the seven exons and a 300 bp promoter region of the PLP gene of two affected brothers. The sequence analysis of a PCR fragment representing exon V amplified from genomic DNA of different kindreds of the pedigree revealed the mother as the only carrier indicating that the mutation has occurred de novo in the mother's germline. PLP gene (including the 8.8 kb intron I) rearrangements have been excluded by Southern blot hybridization and overlapping PCR amplification of genomic DNA.

    Biological chemistry Hoppe-Seyler 1993;374;1;75-83

  • Pelizaeus-Merzbacher disease: detection of mutations Thr181----Pro and Leu223----Pro in the proteolipid protein gene, and prenatal diagnosis.

    Strautnieks S, Rutland P, Winter RM, Baraitser M and Malcolm S

    Molecular Genetics Unit, Institute of Child Health, London, England.

    A family with an apparent history of X-linked Pelizaeus-Merzbacher disease presented for genetic counseling, requesting carrier detection and prenatal diagnosis. RFLP analysis using the proteolipid protein (PLP) gene probe was uninformative in this family. A prenatal diagnosis on a chorionic villus sample (CVS) was carried out using single-strand conformation polymorphism (SSCP) analysis of a variant in exon 4 of the PLP gene. The fetus was predicted to be unaffected. Sequencing of the exon from the CVS, the predicted-carrier mother, and the obligate-carrier grandmother revealed an A-to-C change at nucleotide 541 in the two women but not in the fetus. As this change results in a Thr-to-Pro change at amino acid 181 in a region of the gene predicted to be part of a transmembrane segment, it was concluded that this was the mutation causing the disease in this family. In addition, in a second family, an exon 5 variant band pattern on SSCP analysis was shown by sequencing to be due to a T-to-C change at nucleotide 668. This results in a Leu-to-Pro change in a carrier mother and in her two affected sons. These results provide further examples of mutations in PLP that cause Pelizaeus-Merzbacher disease and illustrate the value of SSCP in genetic analysis.

    American journal of human genetics 1992;51;4;871-8

  • Molecular diagnostics for myelin proteolipid protein gene mutations in Pelizaeus-Merzbacher disease.

    Doll R, Natowicz MR, Schiffmann R and Smith FI

    Division of Biochemistry and Molecular Biology, Eunice K. Shriver Center for Mental Retardation, Waltham, MA 02254.

    Pelizaeus-Merzbacher disease (PMD) is a clinically heterogeneous, slowly progressive leukodystrophy. The recent detection of mutations in the myelin proteolipid protein (PLP) gene in several PMD patients offers the opportunity both to design DNA-based tests that would be useful in diagnosing a proportion of PMD cases and, in particular, to evaluate the diagnostic utility of single-strand conformation polymorphism (SSCP) analysis for this disease. A combination of SSCP analysis and direct sequencing of PCR-amplified DNA was used to screen for PLP mutations in 24 patients affected with leukodystrophies of unknown etiology. Two heretofore undescribed mutations in the PLP gene were identified, Asp202His in exon 4 and Gly73Arg in exon 3. The ease and efficiency of SSCP analysis in detecting new mutations support the utilization of this technique in screening for PLP mutations in patients with unexplained leukodystrophies.

    Funded by: NIDDK NIH HHS: DK38381

    American journal of human genetics 1992;51;1;161-9

  • Pelizaeus-Merzbacher disease: a valine to phenylalanine point mutation in a putative extracellular loop of myelin proteolipid.

    Pham-Dinh D, Popot JL, Boespflug-Tanguy O, Landrieu P, Deleuze JF, Boué J, Jollès P and Dautigny A

    Centre National de la Recherche Scientifique, Unité 1188, Université de Paris, France.

    In the central nervous system, myelin proteolipid protein isoforms (PLP and DM20) play an essential structural role in myelination. It has been shown in several species that myelination is impaired by molecular defects resulting from single base mutations in the PLP gene. We have used DNA amplification by polymerase chain reaction to study the PLP gene coding regions from 17 patients in 15 unrelated families with similar Pelizaeus-Merzbacher phenotype. In one case amplification of peripheral nerve PLP/DM20 cDNAs revealed that a silent T----C transition was unrelated to the disease. In one family a nonsilent mutation was identified that leads to a phenylalanine substitution for valine-218 in PLP/DM20 proteins. We investigated the inheritance of the mutant allele in 19 subjects of this four-generation family and found a strict cosegregation of the Phe218 substitution with transmission and expression of the disease. The effect of the Val218----Phe mutation is discussed in the frame of a recently suggested topological model of PLP/DM20, according to which Val218 is part of an extracellular loop that connects the last two of four membrane-spanning alpha-helices.

    Proceedings of the National Academy of Sciences of the United States of America 1991;88;17;7562-6

  • Major Myelin proteolipid: the 4-alpha-helix topology.

    Popot JL, Pham Dinh D and Dautigny A

    Institut de Biologie Physico-Chimique and Collège de France, C.N.R.S. URA1187, Paris.

    Several conflicting models have been proposed for the membrane arrangement of the major myelin proteolipid (PLP). We have compared features of the sequence of PLP with those of other eukaryotic integral membrane proteins, with the view of identifying the most likely transmembrane topology. A new, simple model is suggested, which features four hydrophobic alpha-helices spanning the whole thickness of the lipid bilayer. Its orientation may be such that both the N- and C-termini face the cytosol. None of the biochemical, biophysical or immunological experiments hitherto reported provides incontrovertible evidence against the model. The effect or absence thereof of various PLP mutations is discussed in the frame of the proposed 4-helix topology.

    The Journal of membrane biology 1991;120;3;233-46

  • A new mutation in the proteolipid protein (PLP) gene in a German family with Pelizaeus-Merzbacher disease.

    Pratt VM, Trofatter JA, Schinzel A, Dlouhy SR, Conneally PM and Hodes ME

    Department of Medical Genetics, Indiana University School of Medicine, Indianapolis 46202-5251.

    A C-to-T transition in exon 4 of the PLP gene was found in 2 affected males and two obligate carriers in a German family with Pelizaeus-Merzbacher disease. The mutation, which causes loss of an HphI site and changes amino acid 155 from threonine to isoleucine, was absent from 108 normal chromosomes. There are 5 concordances and 1 discrepancy between these results and those obtained by magnetic resonance imaging in this family.

    American journal of medical genetics 1991;38;1;136-9

  • A point mutation at the X-chromosomal proteolipid protein locus in Pelizaeus-Merzbacher disease leads to disruption of myelinogenesis.

    Weimbs T, Dick T, Stoffel W and Boltshauser E

    Institut für Biochemie, Medizinische Fakultät, Universität zu Köln.

    A group of inherited neurological disorders are the X-chromosome linked dysmyelinoses, in which myelin membranes of the CNS are missing or perturbed due to a strongly reduced number of differentiated oligodendrocytes. In animal dysmyelinoses (jimpy mouse, msd-mouse, md rat, shaking pup) mutations of the main integral myelin membrane protein, proteolipid protein, have been identified. Pelizaeus-Merzbacher disease (PMD) or sudanophilic leucodystrophy is an X-linked dysmyelinosis in humans. We report here on the molecular basis of the defect of affected males of a PMD kindred. Rearrangements of the PLP gene were excluded by Southern blot hybridisation analysis and PCR amplification of overlapping domains of the PLP gene. Sequence analysis revealed one single C----T transition in exon IV, which leads to a threonine----isoleucine substitution within a hydrophobic intramembrane domain. The impact of this amino-acid exchange on the structure of PLP in the affected cis membrane domain is discussed. A space filling model of this domain suggests a tight packing of the alpha-helices of the loop which is perturbed by the amino-acid substitution in this PMD exon IV mutant. The C----T transition in exon IV abolishes a Hph I restriction site. This mutation at the recognition site for Hph I (RFLP) and allele-specific primers have been used for mutation screening the PMD kindred.

    Biological chemistry Hoppe-Seyler 1990;371;12;1175-83

  • Pelizaeus-Merzbacher disease: tight linkage to proteolipid protein gene exon variant.

    Trofatter JA, Dlouhy SR, DeMyer W, Conneally PM and Hodes ME

    Department of Medical Genetics, Indiana University Medical Center, Indianapolis 46223.

    Pelizaeus-Merzbacher disease (PMD) is a human X chromosome-linked dysmyelination disorder of the central nervous system for which the genetic defect has not yet been established. The jimpy mutation jp of the mouse is an X chromosome-linked disorder of myelin formation. The mutation is at an intron/exon splice site in the mouse gene for proteolipid protein (PLP). With the jimpy mouse mutation as a precedent, we focused our attention on the human PLP gene, which is found at Xq22. The polymerase chain reaction was used to amplify the exons of the PLP gene of an affected male from a large Indiana PMD kindred. DNA sequencing showed a C----T transition at nucleotide 40 of the second exon. An affected third cousin also showed this sequence variation, while two unaffected male relatives (sons of an obligate carrier female) had the normal cytidine nucleotide. Allele-specific oligonucleotides were used to generate data for linkage studies on the above mentioned PMD kindred. Our results show tight linkage (theta = 0) of PMD to PLP with a lod (logarithm of odds) score of 4.62. In six other unrelated PMD kindreds, only the normal-sequence oligonucleotide hybridized, which indicates genetic heterogeneity. The radical nature of the predicted amino acid change (proline to leucine), suggests that the PMD-causing defect may have been delineated in one kindred.

    Proceedings of the National Academy of Sciences of the United States of America 1989;86;23;9427-30

  • Mutation of the proteolipid protein gene PLP in a human X chromosome-linked myelin disorder.

    Hudson LD, Puckett C, Berndt J, Chan J and Gencic S

    Laboratory of Viral and Molecular Pathogenesis, National Institute of Neurological and Communicative Disorders and Stroke, Bethesda, MD 20892.

    Myelin is a highly specialized membrane unique to the nervous system that ensheaths axons to permit the rapid saltatory conduction of impulses. The elaboration of a compact myelin sheath is disrupted in a diverse spectrum of human disorders, many of which are of unknown etiology. The X chromosome-linked human disorder Pelizaeus-Merzbacher disease is a clinically and pathologically heterogeneous group of disorders that demonstrate a striking failure of oligodendrocyte differentiation. This disease appears pathologically and genetically to be similar to the disorder seen in the dysmyelinating mouse mutant jimpy, which has a point mutation in the gene encoding an abundant myelin protein, proteolipid protein (PLP). We report that the molecular defect in one Pelizaeus-Merzbacher family is likewise a point mutation in the PLP gene. A single T----C transition results in the substitution of a charged amino acid residue, arginine, for tryptophan in one of the four extremely hydrophobic domains of the PLP protein. The identification of a mutation in this Pelizaeus-Merzbacher family should facilitate the molecular classification and diagnosis of these X chromosome-linked human dysmyelinating disorders.

    Proceedings of the National Academy of Sciences of the United States of America 1989;86;20;8128-31

  • Pelizaeus-Merzbacher disease: an X-linked neurologic disorder of myelin metabolism with a novel mutation in the gene encoding proteolipid protein.

    Gencic S, Abuelo D, Ambler M and Hudson LD

    Laboratory of Viral and Molecular Pathogenesis, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892.

    The nosology of the inborn errors of myelin metabolism has been stymied by the lack of molecular genetic analysis. Historically, Pelizaeus-Merzbacher disease has encompassed a host of neurologic disorders that present with a deficit of myelin, the membrane elaborated by glial cells that encircles and successively enwraps axons. We describe here a Pelizaeus-Merzbacher pedigree of the classical type, with X-linked inheritance, a typical clinical progression, and a pathologic loss of myelinating cells and myelin in the central nervous system. To discriminate variants of Pelizaeus-Merzbacher disease, a set of oligonucleotide primers was constructed to polymerase-chain-reaction (PCR) amplify and sequence the gene encoding proteolipid protein (PLP), a structural protein that comprises half of the protein of the myelin sheath. The PLP gene in one of two affected males and the carrier mother of this family exhibited a single base difference in the more than 2 kb of the PLP gene sequenced, a C----T transition that would create a serine substitution for proline at the carboxy end of the protein. Our results delineate the clinical features of Pelizaeus-Merzbacher disease, define the possible molecular pathology of this dysmyelinating disorder, and address the molecular classification of inborn errors of myelin metabolism. Patients with the classical form (type I) and the more severely affected, connatal variant of Pelizaeus-Merzbacher disease (type II) would be predicted to display mutation at the PLP locus. The other variants (types III-VI), which have sometimes been categorized as Pelizaeus-Merzbacher disease, may represent mutations in genes encoding other structural myelin proteins or proteins critical to myelination.

    American journal of human genetics 1989;45;3;435-42

  • Interaction of myelin basic protein and proteolipid protein.

    Edwards AM, Ross NW, Ulmer JB and Braun PE

    Department of Biochemistry, McGill University, Montreal, Quebec, Canada.

    The interaction of myelin basic protein (MBP) and proteolipid protein (PLP) was studied using a microtitre well binding assay and the ligand-blot overlay technique. The binding of iodinated PLP to MBP that was immobilized on microtitre wells was saturable and reversible. Its selectivity was investigated by the ligand-blot overlay technique. Iodinated PLP was found to bind MBP but not any other CNS myelin proteins. This interaction was not dependent on the phosphoryl moiety of MBP. Binding of PLP to histone H4 also occurred, but the amount of PLP bound per unit MBP was greater than for this histone.

    Journal of neuroscience research 1989;22;1;97-102

  • Human myelin DM-20 proteolipid protein deletion defined by cDNA sequence.

    Simons R, Alon N and Riordan JR

    Using a myelin proteolipid protein (PLP) cDNA as probe, a 1kb cDNA was isolated from a human retinal cDNA library. This clone, designated pDM-20, contained all of the coding sequence of PLP except for 105 base pairs which encode amino acids 117-151 of PLP. This deletion would result in a protein of the size of DM-20, the second major proteolipid of Central Nervous System (CNS) myelin. Homology between the DNA sequence at the 5' end of the deletion and the donor splicing consensus sequence suggests that PLP and DM-20 transcripts are derived from a single PLP gene by alternate splicing.

    Biochemical and biophysical research communications 1987;146;2;666-71

  • Expression of myelin proteins in the developing human spinal cord: cloning and sequencing of human proteolipid protein cDNA.

    Kronquist KE, Crandall BF, Macklin WB and Campagnoni AT

    Mental Retardation Research Cener, U.C.L.A. School of Medicine 90024.

    A full-length clone for the human proteolipid protein (PLP) was isolated from a cDNA library constructed from poly(A)+ RNA isolated from fetal spinal cords obtained at 15-24 weeks of conceptional age. The sequence of the human PLP cDNA was determined, and the deduced amino acid sequence was found to be identical with that of rat PLP. Comparison of human and rat PLP cDNA clones indicated that the coding regions retained 97% homology and that there were also other areas of conserved sequence. The human 5'-untranslated region was 93% homologous to that of the rat. The 3'-untranslated region was, overall, 73% homologous to that of the rat with areas containing greater than 84% homology in the first 400 and last 200 nucleotides. The most variability within the 3'-untranslated region occurred between nucleotides 2,000-2,500, where homology with the rat cDNA dropped to 55%. Expression of PLP in the human spinal cord between 11 and 23 weeks after conception was examined and compared with the expression of the myelin basic protein (MBP). RNA was isolated from pooled human spinal cords obtained at three periods of development: 11-14 weeks, 17-19 weeks, and 21-23 weeks. Northern blot analysis revealed a 3.2-kilobase (kb) PLP mRNA that was present at higher abundance in the 21-23-week spinal cord RNA than in the 17-19-week or the 11-14-week samples. The 17-19-week RNA sample also contained a PLP-hybridizing band at 2.2 kb which may possibly have arisen by utilization of alternative polyadenylation signals. Messenger RNA for MBP was detectable at 11-14 weeks but was readily evident in both the 17-19- and 21-23-week age groups. Immunoblot analysis of whole spinal cord homogenates indicated that polypeptides for MBP preceded the appearance polypeptides for PLP by 3-4 weeks.

    Funded by: NCRR NIH HHS: RR5756; NINDS NIH HHS: NS23022, NS23322, R01 NS025304

    Journal of neuroscience research 1987;18;3;395-401

  • Individual exons encode the integral membrane domains of human myelin proteolipid protein.

    Diehl HJ, Schaich M, Budzinski RM and Stoffel W

    The gene encoding human proteolipid protein (PLP) was isolated from a human genomic library by hybridization with labeled DNA of a PLP-specific cDNA clone. The entire PLP gene spans approximately 17 kilobases. Restriction and sequence analysis revealed seven exons and six introns. The entire nucleotide sequences of the exons and of the exon-intron transitions were determined, and the intron lengths were measured. Exon I includes only ATGG of the translated region, the N-terminal methionine codon and G of glycine, the first amino acid of mature PLP. Each hydrophobic trans- and cis-membrane domain of PLP together with its adjacent hydrophilic sequence correlates closely with one exon of the gene except for the C-terminal transmembrane helix that is encoded by two exons. The amino acid sequence of human PLP derived from the nucleic acid sequence is highly conserved. Human and rat PLP are completely homologous, whereas only four amino acid residues are exchanged in bovine PLP sequence derived from protein sequencing and a partial cDNA clone. Homology search on the nucleic acid level among human, bovine, and rat brain PLPs indicates an unusually high homology in the coding regions. Hybridization analysis with DNA of human-rodent hybrid clones revealed that the gene encoding PLP segregates with human X chromosome in the region q13-q22.

    Proceedings of the National Academy of Sciences of the United States of America 1986;83;24;9807-11

  • The intramembranous domains of lipophilin in phosphatidylcholine vesicles are similar to those in the myelin membrane.

    Kahan I and Moscarello MA

    A membrane-permeable photolabel 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine (125I-TID) has been used to label lipophilin in normal human myelin and after incorporation of purified lipophilin into phosphatidylcholine (PC) vesicles. The labelled protein was isolated and the specific activities for lipophilin from myelin and from PC vesicles was found to be 1.2 X 10(11) and 1.5 X 10(11) cpm/mol, respectively. The chromatographic profiles of tryptic peptides were similar in both cases and the specific activities of the C-terminal intramembranous fragments (residues 205-268) the same. We concluded that the organization of lipophilin in PC vesicles was similar to its organization in myelin and that the PC-vesicle system represents a good system in which to study the orientation and interaction of lipophilin with lipids.

    Biochimica et biophysica acta 1986;862;1;223-6

  • The gene encoding for the major brain proteolipid (PLP) maps on the q-22 band of the human X chromosome.

    Mattei MG, Alliel PM, Dautigny A, Passage E, Pham-Dinh D, Mattei JF and Jollès P

    Recombinant plasmid clone p23 containing the cDNA proteolipid (PLP) sequence was localized by in situ hybridization on band q22 of the human X chromosome. This localization may have implications for X-linked demyelination diseases such as Pelizaeus-Merzbacher disease in man.

    Human genetics 1986;72;4;352-3

  • Assignment of the gene for myelin proteolipid protein to the X chromosome: implications for X-linked myelin disorders.

    Willard HF and Riordan JR

    Several inherited disorders in humans and in rodents result in myelin dysgenesis and a deficiency of the molecular constituents of myelin. A complementary DNA to one of the two major myelin proteins, myelin proteolipid protein (also known as lipophilin), has been used with Southern blot analysis of somatic cell hybrid DNA to map the human proteolipid protein gene to the middle of the long arm of the human X chromosome (bands Xq13-Xq22) and to assign the murine proteolipid protein gene to the mouse X chromosome. Comparison of the gene maps of the human and mouse X chromosomes suggests that myelin proteolipid protein may be involved in X-linked mutations at the mouse jimpy locus and has implications for Pelizaeus-Merzbacher disease, a human inherited X-linked myelin disorder.

    Science (New York, N.Y.) 1985;230;4728;940-2

  • Amino-acid sequence of human and bovine brain myelin proteolipid protein (lipophilin) is completely conserved.

    Stoffel W, Giersiefen H, Hillen H, Schroeder W and Tunggal B

    Proteolipid protein (PLP) was isolated from white matter of human brain by chloroform/methanol extraction and further purified by chromatography. Performic acid oxidation yielded a product homogeneous in NaDodSO4-polyacrylamide electrophoresis with a molecular mass of 30 kDa. The carboxymethylated PLP was chemically cleaved with cyanogen bromide into four fragments: CNBr I 22-24 kDa, CNBr II 5 kDa, CNBr III 1.4 kDa and CNBr IV 0.7 kDa. HBr/dimethylsulfoxide cleavage at tryptophan residues released four fragments: Trp I 14-16 kDa, Trp II 2.0 kDa, Trp III 5 kDa and Trp IV 7 kDa. Hydrophilic fragments were enriched in 50% formic acid (CNBr II, III, IV and Trp II and III), whereas hydrophobic peptides precipitated from this solvent were CNBr I, Trp I and IV. The fragments were separated by gel filtration with 90% formic acid as solvent and finally purified by gel permeation HPLC (Si 60 and Si 100) for automated liquid and solid-phase Edman degradation. Large fragments were further cleaved with different proteinases (trypsin, V8-proteinase, endoproteinase Lys-C and thermolysin). We used an improved strategy in the sequencing of the human proteolipid protein compared with our approach to the structural elucidation of bovine brain PLP. The amino-acid sequence of human PLP contains 276 residues, the same as found in bovine proteolipid protein. The two sequences proved to be identical. The possible importance of the conservative structure of this integral membrane protein is discussed.

    Biological chemistry Hoppe-Seyler 1985;366;7;627-35

  • Interaction between human myelin basic protein and lipophilin.

    Wood DD, Vella GJ and Moscarello MA

    The interaction of human myelin basic protein with lipophilin has been demonstrated by affinity chromatography. The interaction was specific since neither basic protein, nor albumin bound to an affinity column consisting of BP bound to agarose. Conversely an albumin affinity column failed to bind BP. The pH dependency of the interaction correlated with the known pK for histidine. By the use of large peptides formed by tryptophanyl cleavage by BNPS-skatole, peptide 1-117 bound to the BP affinity column while neither the smaller peptide, 118-170, nor the synthetic nonapeptide bound. The large fragment contains 9 of the 10 histidines in the molecule which may explain the binding of this fragment. The result of such protein-protein interactions makes available a large number of new antigenic sites and extends considerably the range of encephalitogens for disease induction.

    Neurochemical research 1984;9;10;1523-31

  • Regional studies of myelin proteins in human brain and spinal cord.

    Trotter JL, Wegescheide CL and Garvey WF

    The myelin specific proteins, myelin basic protein (MBP) and myelin proteolipid protein (PLP) were quantitated by radioimmunoassay (RIA) and the activity of the enzyme 2',3'-cyclic 3' phosphohydrolase (CNP) measured, in 27 regions of normal brain and spinal cord. Varying regional concentrations for each protein and regional variations for protein ratios were noted, supporting the concept of a varying chemical composition for myelin throughout the central nervous system (CNS). Variation was also noted among myelin subfractions from a single region. Regions with special sensitivity to the multiple sclerosis process had relatively lower proportions of CNP in several, but not all cases.

    Funded by: NINDS NIH HHS: NS00221

    Neurochemical research 1984;9;1;133-46

Gene lists (9)

Gene List Source Species Name Description Gene count
L00000009 G2C Homo sapiens Human PSD Human orthologues of mouse PSD adapted from Collins et al (2006) 1080
L00000014 G2C Homo sapiens Human ARC Human orthologues of mouse AMPA receptor complex adapted from Collins et al (2006) 9
L00000015 G2C Homo sapiens Human NRC Human orthologues of mouse NRC adapted from Collins et al (2006) 186
L00000016 G2C Homo sapiens Human PSP Human orthologues of mouse PSP adapted from Collins et al (2006) 1121
L00000049 G2C Homo sapiens TAP-PSD-95-CORE TAP-PSD-95 pull-down core list (ortho) 120
L00000059 G2C Homo sapiens BAYES-COLLINS-HUMAN-PSD-CONSENSUS Human cortex PSD consensus 748
L00000061 G2C Homo sapiens BAYES-COLLINS-MOUSE-PSD-CONSENSUS Mouse cortex PSD consensus (ortho) 984
L00000069 G2C Homo sapiens BAYES-COLLINS-HUMAN-PSD-FULL Human cortex biopsy PSD full list 1461
L00000071 G2C Homo sapiens BAYES-COLLINS-MOUSE-PSD-FULL Mouse cortex PSD full list (ortho) 1556
© G2C 2014. The Genes to Cognition Programme received funding from The Wellcome Trust and the EU FP7 Framework Programmes:
EUROSPIN (FP7-HEALTH-241498), SynSys (FP7-HEALTH-242167) and GENCODYS (FP7-HEALTH-241995).

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