A Family with Subclinical Charcot-Marie-Tooth Disease Associated with a Mutation in the MPZ Gene

Charcot-Marie-Tooth (CMT) disease is an inherited neuropathy characterized by progressive motor and sensory impairment. Mutations in the myelin protein zero (MPZ) gene are the second most common cause of CMT and are often associated with severe clinical presentations. We describe the case of a 31-year-old woman who had an incidental diagnosis of an intermediate neuropathy on nerve conduction studies, without any symptoms or clinical signs. Genetic analysis identified a novel MPZ mutation, c.275dup [p.(Thr94Aspfs*28)], predicted to produce a truncated, non-functional protein. Over a follow-up period of seven years the patient remains asymptomatic. The patient’s father, also asymptomatic and without findings relevant to observation, presented similar alterations in nerve conduction studies, but did not undergo genetic studies. This case broadens the known phenotypic spectrum of MPZ-related neuropathies and suggests that additional genetic or epigenetic factors may influence disease expression.