Variability of disease progression in a family with autosomal recessive CMT associated with a S194X and new R310Q mutation in the GDAP1 gene.

Charcot-Marie-Tooth (CMT) with autosomal recessive (AR) inheritance is a heterogeneous group of inherited motor and sensory neuropathies. Six genes and five additional loci have been identified that are responsible for either demyelinating or axonal forms of the disease. The gene encoding the ganglioside-induced-differentiation-associated protein 1 (GDAP1) has been associated with both demyelinating and axonal phenotypes. We report a detailed clinical, electrophysiological, and genetic study of two siblings from a Moroccan ARCMT family who are compound heterozygotes for the already described S194X and a new R310Q mutation in the GDAP1 gene. The electrophysiological data are compatible with an axonal form of the disease. The phenotype included hoarse voice and paralysis of the diaphragm. This study shows the variability of the phenotype associated with mutations in GDAP1 gene in terms of associated signs and severity.