Clinical and Genetic Analysis of an Asian Indian Family with Charcot-Marie-Tooth Disease Type 4C

Abstract

Charcot-Marie-Tooth disease type 4C, an autosomal recessive genetic neuropathy, is caused by mutations in the SH3TC2 (SH3 domain and tetratricopeptide repeats 2) gene. Interestingly, although mutations in this gene have been observed in European gypsies, a population that originated in India, there are few publications describing Indian patients. We report our analysis of a 50-year-old woman of Asian Indian descent with onset of progressive distal weakness and sensory loss in childhood. A clinical examination revealed the presence of a neuropathy with pes cavus without spinal abnormalities. Electrophysiological testing confirmed a sensorimotor length-dependent neuropathy with demyelinating features. A genetic analysis revealed she carries 2 novel mutations, c.2488G>T variant (rs879254317) and c.731+5G>A variant (rs879254316), in the SH3TC2 gene. Further genetic testing demonstrated that her son is a carrier of the c.731+5G>A mutation. Our analysis confirms that this patient is a compound heterozygote inheriting these mutations, which are in trans, in an autosomal recessive pattern. Her son developed an episode of sciatic neuropathy with complete resolution. We hypothesize that in his case, haploinsufficiency caused by c.731+5G>A mutation may have predisposed him to the development of this focal neuropathy.

Keywords

• Charcot-Marie-Tooth disease type 4C
• SH3TC2 gene
• Novel variants
• Asian Indian