Clinical, Electrophysiological and Genetic Studies of Two Families with Mutations in the GDAP1 Gene

Mutations in the gene for the ganglioside-induced-differentiation-associated-protein 1 on 8q21 were recently reported to cause autosomal recessive Charcot-Marie-Tooth sensorimotor neuropathy. We report a detailed clinical, electrophysiological and genetic study of two young patients harbouring missense GDAP1 mutations. The two patients presented severe neuropathy with an early onset. One of the mutations (Tyr-279Cys) has never been hitherto reported. Electrophysiological investigations suggested a predominant axonal damage in both patients. Despite the similitude of the type of mutations and electromyographic features, the clinical course was different for the patients, highlighting the complexity of genotype/phenotype relationships among GDAP1 mutations.