Coexistent Charcot-Marie-Tooth type 1A and type 2 diabetes mellitus neuropathies in a Chinese family.

Charcot-Marie-Tooth disease type 1A (CMT1A) is caused by duplication of the peripheral myelin protein 22 (PMP22) gene on chromosome 17. It is the most common inherited demyelinating neuropathy. Type 2 diabetes mellitus is a common metabolic disorder that frequently causes predominantly sensory neuropathy. In this study, we report the occurrence of CMT1A in a Chinese family affected by type 2 diabetes mellitus. In this family, seven individuals had duplication of the PMP22 gene, although only four had clinical features of polyneuropathy. All CMT1A patients with a clinical phenotype also presented with type 2 diabetes mellitus. The other three individuals had no signs of CMT1A or type 2 diabetes mellitus. We believe that there may be a genetic link between these two diseases.