Type 2 Charcot-Marie-Tooth disease

Introduction and development. Type 2 Charcot-Marie-Tooth disease (CMTD-2) is of similar prevalence to CMTD-1. The age of onset is very variable (ranging between the second and seventh decades). It is impossible to clinically differentiate CMTD-1 from type 2, but for equivalent degrees of muscle weakness, amyotrophia is more marked in the latter The speed of motor and sensory nerve conduction are normal or minimally slower (greater than or equal to 38 m/s) and accompanied by a fall in the nerve potentials of the lower limbs, but not always in the upper limbs. These electrophysiological anomalies do not occur early and therefore do not permit rapid presymptomatic diagnosis of carriers at risk. The histopathological changes are compatible with primary atrophy of the motor neurons of the anterior horns and of the sensory neurons of the ganglia of the posterior roots with secondary degeneration of the distal axons of the peripheral nerves. Autosomal dominant transmission is the main mode of inheritance, but only a minority of families have genetic loci situated on chromosomes 1,3 and 7. Conclusion. The first step in rapid molecular diagnosis and genetic treatment is to identify the genes situated in the currently known loci and discover new loci.