ABSTRACT
Charcot-Marie-Tooth disease (CMT) constitutes a genetically heterogeneous group of inherited motor and sensory peripheral neuropathies. The axonal type of CMT is designated CMT type 2 (CMT2). Four loci for autosomal dominant CMT2 have been reported so far. Only in CMT2E, linked to chromosome 8p21, disease-causing mutations in the gene for neurofilament light chain (NEFL) were identified. In this study we report a multigenerational Russian family with autosomal dominant CMT2 and assign the locus to chromosome 7q11-q21. The CMT2 neuropathy in this family represents a novel genetic entity designated CMT2F.
Subject(s)
Charcot-Marie-Tooth Disease/genetics , Chromosome Mapping , Chromosomes, Human, Pair 7/genetics , Genes, Dominant/genetics , Adolescent , Adult , Child , Child, Preschool , Female , Genetic Markers/genetics , Humans , Infant , Infant, Newborn , Male , PedigreeABSTRACT
Charcot-Marie-Tooth disease (CMT) and related inherited peripheral neuropathies, including Dejerine-Sottas syndrome, congenital hypomyelination, and hereditary neuropathy with liability to pressure palsies (HNPP), are caused by mutations in three myelin genes: PMP22, MPZ and Cx32 (GJB1). The most common mutations are the 1.5 Mb CMT1A tandem duplication on chromosome 17p11.2-p12 in CMT1 patients and the reciprocal 1.5 Mb deletion in HNPP patients. We performed a mutation screening in 174 unrelated CMT patients and three HNPP families of Russian origin. The unrelated CMT patients included 108 clinically and electrophysiologically diagnosed CMT1 cases, 32 CMT2 cases, and 34 cases with unspecified CMT. Fifty-nine CMT1A duplications were found, of which 58 belonged to the CMT1 patient group. We found twelve distinct mutations in Cx32, six mutations in MPZ, and two mutations in PMP22. Of these respectively, eight, five, and two lead to a CMT1 phenotype. Eight mutations (Cx32: Ile20Asn/Gly21Ser, Met34Lys, Leu90Val, and Phe193Leu; MPZ: Asp134Gly, Lys138Asn, and Thr139Asn; PMP22: ValSer25-26del) were not reported previously. Phenotype-genotype correlations were based on nerve conduction velocity studies and mutation type.
