Clinical and electrophysiological studies of a family with probable X-linked dominant Charcot-Marie-Tooth neuropathy and ptosis

Abstract

Background: The X-linked dominant Charcot-Marie-Tooth neuropathy (CMTX) is a hereditary motor and sensory neuropathy linked to a variety of mutations in the connexin32 (Cx32) gene. Clinical and genetic features of CMTX have not previously been reported in Taiwanese.

Methods: Clinical evaluations and electrophysiological studies were carried out on 25 family members of a Taiwanese family group. Molecular genetic analysis of the Cx32 gene was performed. A sural nerve biopsy was obtained from 1 patient.

Results: Nine patients had clinical features of X-linked dominant inheritance and a moderate Charcot-Marie-Tooth (CMT) neuropathy phenotype. Molecular genetic analysis showed no mutation of the Cx32 coding region, but revealed a G-to-A transition at position -215 of the nerve-specific promoter P2 of the Cx32 gene. Ptosis is 1 clinical manifestation of neuropathy in this probable CMTX family. Familial hyperthyroidism is an additional independent feature of the family. Electrophysiological and histological studies showed features of axonal neuropathy. Multimodality evoked potential studies revealed normal central motor and sensory conduction velocities.

Conclusions: The presence of ptosis in this family illustrates the existence of clinical heterogeneity among related family members with CMTX similar to that in CMT of autosomal inheritance. Electrophysiological and histological findings revealed normal central conduction and axonal neuropathy.