Axonal and demyelinating forms of the MPZ Thr124Met mutation.

Objective – We report on a Japanese family with Charcot–Marie–Tooth disease (CMT) with the Thr124Met mutation in the peripheral myelin protein zero (MPZ) gene. Material and methods – Based on the clinical study, we investigated MPZ gene by direct sequence analysis and polymerase chain reaction–restriction fragment length polymorphism analysis. Results – Genotyping of four symptomatic family members showed that one family member with severe disease symptoms was homozygous, while the other three were heterozygous. The heterozygous cases were clinicopathologically determined to be the axonal type, which is characterized by late-onset and slow progression associated with Adie's pupil and deafness. The homozygous case was the demyelinating type, which showed earlier onset, rapid progression, sural nerve demyelination, and cranial nerve demyelination at autopsy. Conclusions – We suggest that axonal and demyelinating forms of CMT are not two distinct classes, but rather parts of a spectrum of genotypically related conditions, particularly with some MPZ mutations.