Clinical and genetic spectra in a series of Chinese patients with Charcot-Marie-Tooth disease

Abstract

The aim of this study was to determine the clinical features and frequencies of genetic subtypes in a series of patients with Charcot-Marie-Tooth (CMT) disease from Eastern China. Patients were divided into three subtypes, CMT1, CMT2 and hereditary neuropathy with liability to pressure palsy (HNPP), according to their electrophysiological manifestations. Multiplex ligation-dependent probe analysis (MLPA) was performed to detect duplications/deletions in the PMP22 gene. The coding regions and splice sites of the GJB1, MPZ, MFN2 and GDAP-1 genes were determined by direct sequencing. Among the 148 patients in the study, 37.2% of the cases had mutations in genes assessed. The mutation detection rate was higher in patients with family histories than in spontaneous cases. PMP22 duplication (13.5%) was predominant in this group of patients, followed by PMP22 deletion (11.5%), and point mutations in GJB1 (8.8%), MPZ (2.0%) and MFN2 (0.7%). Three novel mutations (c.151T>C and c.310 A>G in GJB1 and c.1516 C>G in MFN2) were detected. A small deletion in PMP22 exon 4 was detected in a patient with severe CMT1. Genetic tests have great value in CMT patients with family histories. The frequency of PMP22 duplications was lower in Asian patients than in others. We suggest that genetic testing strategies in CMT patients should be primarily based on electromyography data.

Keywords: Charcot–Marie–Tooth; Clinical feature; Electrophysiological evaluation; Gene mutation.