Genetic transmission of migraine without aura: a study of 68 families.

68 randomly selected patients with migraine without aura (M) and 4 generations of their relatives (N = 394) were studied in order to probe the genetic hypothesis of migraine. Significantly more of the probands were women and M was significantly more frequent among female relatives. Earlier onset was commoner among male probands. A genetic component of M is indicated by the very high frequency of at least one affected relative (85.3%) and by a disease prevalence that is similar among both first and second degree relatives. A simple autosomal mode of transmission seems unlikely from analysis of the data on the affected relatives, while a "sex-limited" transmission mode is suggested.