title: Mutations in the gene encoding gap junction protein alpha 12 (connexin 46.6) cause Pelizaeus-Merzbacher-like disease.
abstract: The hypomyelinating leukodystrophies X-linked Pelizaeus-Merzbacher disease (PMD) and Pelizaeus-Merzbacher-like disease (PMLD) are characterized by nystagmus, progressive spasticity, and ataxia. In a consanguineous family with PMLD, we performed a genomewide linkage scan using the GeneChip Mapping EA 10K Array (Affymetrix) and detected a single gene locus on chromosome 1q41-q42. This region harbors the GJA12 gene, which encodes gap junction protein alpha 12 (or connexin 46.6). Gap junction proteins assemble into intercellular channels through which signaling ions and small molecules are exchanged. GJA12 is highly expressed in oligodendrocytes, and, therefore, it serves as an excellent candidate for hypomyelination in PMLD. In three of six families with PMLD, we detected five different GJA12 mutations, including missense, nonsense, and frameshift mutations. We thereby confirm previous assumptions that PMLD is genetically heterogeneous. Although the murine Gja12 ortholog is not expressed in sciatic nerve, we did detect GJA12 transcripts in human sciatic and sural nerve tissue by reverse-transcriptase polymerase chain reaction. These results are in accordance with the electrophysiological finding of reduced motor and sensory nerve conduction velocities in patients with PMLD, which argues for a demyelinating neuropathy. In this study, we demonstrate that GJA12 plays a key role in central myelination and is involved in peripheral myelination in humans.
authors.affiliation: Department of Neuropediatrics, Charité, University Medical School of Berlin, Berlin, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Uhlenberg
authors.forename: Markus
authors.initials: M
authors.lastname: Schuelke
authors.forename: Franz
authors.initials: F
authors.lastname: Rüschendorf
authors.forename: Nico
authors.initials: N
authors.lastname: Ruf
authors.forename: Angela M
authors.initials: AM
authors.lastname: Kaindl
authors.forename: Marco
authors.initials: M
authors.lastname: Henneke
authors.forename: Holger
authors.initials: H
authors.lastname: Thiele
authors.forename: Gisela
authors.initials: G
authors.lastname: Stoltenburg-Didinger
authors.forename: Fuat
authors.initials: F
authors.lastname: Aksu
authors.forename: Haluk
authors.initials: H
authors.lastname: Topaloğlu
authors.forename: Peter
authors.initials: P
authors.lastname: Nürnberg
authors.forename: Christoph
authors.initials: C
authors.lastname: Hübner
authors.forename: Bernhard
authors.initials: B
authors.lastname: Weschke
authors.forename: Jutta
authors.initials: J
authors.lastname: Gärtner
mesh_terms: D000595:Amino Acid Sequence; D017630:Connexins / Q000235:genetics*; D005260:Female; D006239:Haplotypes; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009420:Nervous System / Q000378:metabolism / Q000503:physiopathology; D010375:Pedigree; D020371:Pelizaeus-Merzbacher Disease / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D017433:Protein Structure, Secondary
chemical_list: D017630:Connexins; C082917:GJA3 protein, human