Graves' disease and subarachnoid hemorrhage: a possible familial association.

We report the occurrence of cerebral aneurysms and subarachnoid hemorrhage (SAH) in a family with Graves' disease (GD). Nine affected individuals across three generations have GD alone; three in the same generation have SAH without GD; and three others in the same sibship have both conditions. The familial association of GD and SAH has not been previously described. The occurrence of these disorders in individuals of the same family and their coexistence in the same individuals suggests a possible genetic determination for some cerebral aneurysms and may imply a genetic locus related to that of Graves' disease.