Klinefelter's syndrome associated with progressive muscular atrophy simulating Kennedy's disease.

Kennedy's disease, an X-linked spinal and bulbar muscular atrophy, is characterized by loss of lower motor neurons. Mild sensory deficits, gynecomastia and infertility may be observed. Klinefelter's syndrome is a variation of sex chromosome disorder characterized by hypogonadism, gynecomastia and azoospermia, and the most frequent karyotype is XXY. A 55-year-old man who presented with slowly progressive and diffuse neurogenic muscle atrophy without bulbar or sensory symptoms. He also had Klinefelter's syndrome. Genetic study of Kennedy's disease was normal. Our patient differs from those with Kennedy's disease in the absence of bulbar and sensory symptoms. It is suggested that the X chromosome plays an important role in the biology of motor neurons.