Genetics of migraine and other headache.

Recent progress in the genetics of migraine and other headache syndromes occurred in three major areas during the past year: systematic family studies of migraine, large-scale population-based twin studies, and linkage and association studies of familial hemiplegic migraine. Studies of linkage between familial hemiplegic migraine and marker 19p13 in 13 extended families have found a total of seven families with linkage to this region. Three large scale population-based twin studies of headache have revealed that approximately one-half of the variation in migraine could be attributable to additive genes, with the remainder primarily caused by unshared rather than shared environmental factors between twins. Migraine is clearly a complex disease characterized by high population prevalence, an inconclusive mode of transmission, and a lack of clear evidence for phenotypic validity. Increasing knowledge from family and twin studies using contemporary diagnostic methods will help to clarify the factors contributing to the heterogeneity of this condition.