Median nerve motor conduction velocity is concordant with myelin protein zero gene mutation

Background Myelin protein zero gene (MPZ) mutations may account for a small proportion of cases of Charcot-Marie-Tooth disease (CMT). Different MPZ mutations may be associated with different clinical and electrophysiological phenotypes. Objectives To expand our understanding of the characteristics of nerve conduction velocity (NCV) in patients with different MPZ mutations, the authors collected and analysed the NCV values from patients with MPZ mutations. Materials and Methods The NCVs of fourteen patients from six families carrying MPZ mutations of Val58Asp, Ser63Phe, Thr65Ile, Arg98Cys, Arg98His, and Ser233fs were collected retrospectively. Five of them had received nerve conduction studies (NCS) twice. The mutations were verified by polymerase chain reaction (PCR) amplifications and nucleotide sequencing. Scatterplot analyses of median motor NCV (MNCV) versus specific MPZ mutation were performed. Results The median MNCV varied widely, with a mean of 16.3 m/s ( SD= 7.7 m/s) and a range of 5.1 - 32.9 m/s. Median MNCVs of patients with particular MPZ mutations were similar. Moreover, Median MNCV did not change significantly over time. Conclusions There was concordance between median MNCV and specific MPZ mutations. However, median MNCV is not an ideal measure with which to distinguish CMT1B patients with MPZ mutations from CMT1A patients with PMP22 mutations.