Adult onset axonal Charcot-Marie-Tooth disease with autonomic features in a family with the Thr124Met mutation of MPZ
Objective: We report the case of a 51 year old man with a ten year history of progressive sensori-motor Charcot-Marie-Tooth (CMT) disease and documented Thr124Met mutation of the Myelin Protein Zero (MPZ) gene. This individual was one of four affected members in his large family of Vietnamese-Chinese ethnic background. The condition exhibited an autosomal dominant pattern of inheritence. Affected individuals presented with length dependent sensori-motor polyneuropathy with symptom onset from 40 to 50 years of age. In our case, symptoms developed at the age of 41 years with progressive paraesthesia, weakness and severe sensory loss affecting the distal lower limbs. Examination revealed evidence of a severe length dependent sensori-motor polyneuropathy with wasting, weakness and sensory loss to the knees and absent lower limb reflexes. The hands were less involved. Bilateral tonic pupils were evident and the patient described urinary dysfunction. Nerve conduction studies revealed a severe axonal sensori-motor polyneuropathy. Autonomic, respiratory function and audiometric testing was performed and will be discussed. A Thr124Met missense mutation was identifed within MPZ gene.
Conclusion: We present a case of late onset, severe axonal, sensori-motor CMT with autonomic features caused by a Thr124Met mutation within the MPZ gene. Mutations of MPZ were originally classified as causing demyelinating sensori-motor CMT (type 1B), but mutations of MPZ - such as Thr124Met - should be considered in axonal forms of autosomal dominant CMT.