[Molecular diagnosis of hereditary neuropathies such as Charcot-Marie-Tooth disease]

During the last decade, molecular biology has demonstrated the extraordinary heterogeneity of genetic abnormalities in Charcot-Marie-Tooth disease (CMT). The main phenotypes are either of the demyelinating or axonal type, transmitted with dominant or recessive autosomal inheritance. X-linked CMT is less rare than it was initially described and is often misdiagnosed as autosomal dominant type. Linked phenotypes are Dejerine-Sottas disease, congenital hypomyelinization and hereditary neuropathy with susceptibility to pressure palsies. Each phenotype can be due to different genotypes and concerned genes are numerous. Conversely, each genotype can express different phenotypes. Molecular diagnostic strategy of CMT is mainly baised on three elements: - phenotypic expertise which is based on the analysis of the inheritance mode and on electrophysiological data, which are peculiar in CMTX - knowledge of respective occurrence of the different genotypes and phenotypes which is increasing - technical feasibility of molecular biology methods which is important to consider, even though progress are fastly coming. According to these considerations, a strategy is proposed for molecular diagnosis of CMT.