[XYY syndrome associated with motor neuropathy].

We described a case of XYY syndrome associated with motor neuropathy. The case was a 27-year-old male, who had 47-XYY chromosome karyotype. His symptoms were distal dominant muscle weakness and muscle atrophy in his lower extremities without objective sensory disturbance. He had no mental retardation or family history of neurologic diseases. The electrophysiological and pathological examinations revealed that his symptoms were due to peripheral motor neuropathy (neuronal type). His motor neuropathy may be of sporadic type. There may be some relation in the pathogenesis between XYY syndrome and motor neuropathy, although in the literature, XYY syndrome with motor neuropathy had not been reported so far.