Pelizaeus-Merzbacher Disease: A Valine to Phenylalanine Point Mutation in a Putative Extracellular Loop of Myelin Proteolipid

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 88; no. 17; pp. 7562 - 7566
• Main Authors: PHAM-DINH, D, POPOT, J.-L, BOESPFLUG-TANGUY, O, LANDRIEU, P, DELEUZE, J.-F, BOUE, J, JOLLES, P, DAUTIGNY, A
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.09.1991; National Acad Sciences
• Subjects: Alleles; Animals; Base Sequence; Biological and medical sciences; Cells, Cultured; Central nervous system; Complementary DNA; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Diffuse Cerebral Sclerosis of Schilder - genetics; DNA; DNA - genetics; DNA - isolation & purification; Exons; Female; Genetic mutation; Humans; Male; Medical sciences; Molecular Sequence Data; Mutation; Myelin; Myelin Proteins - genetics; Myelin Proteolipid Protein; Neurology; Oligonucleotide Probes; Oligonucleotides; Pedigree; Pelizaeus Merzbacher disease; Phenylalanine; point mutation; Polymerase chain reaction; Polymerase Chain Reaction - methods; Protein Conformation; Human; Polymerase chain reaction; Nervous system diseases; Pelizaeus-Merzbacher disease; Myelin; Aminoacid; Point mutation; Metabolic diseases; Lipoprotein; Genetic disease
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.88.17.7562

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 Phe218substitution 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 Val218is part of an extracellular loop that connects the last two of four membrane-spanning α-helices.