Familial migraine in a Mexican population.

We investigated the frequency of migraine in first-degree relatives of a group of migraine patients in two Mexican populations, one urban and one rural, and in control groups from the same populations. In the urban population, familial aggregation of migraine was found in 52.7% of patients and in the rural in 38.7%. The differences between controls and subjects were statistically significant in both populations. Our findings support the importance of a hereditary factor in migraine but not an autosomal dominant inheritance pattern.