Familial occurrence of moya-moya disease: report of three Japanese families.

Three Japanese families with moya-moya disease in six patients are presented. These six patients were among 49 cases of confirmed moya-moya disease in our experience, and the familial incidence was more than 12%. A relatively high familial incidence (7%) was found in the total Japanese series emphasising the important hereditary components in the pathogenesis of the disease.