Autosomal dominant cramping disease.

A family was studied in which four generations (16 of 41 members) suffered from painful recurrent muscle cramping. A clear pattern of autosomal dominant inheritance was noted. The cramping first developed during adolescence or early adulthood. Electromyographic analysis indicated a neurogenic origin. The cramps seemed to be due to dysfunction of the motor neurons. The mechanisms underlying this alteration are unclear and require further investigation.