The association of affective disorder with Huntington's disease in a case series and in families.

Major affective disorder clinically similar to the disorder found in conditions other than Huntington's Disease (HD) was found in 41% of patients with HD in a consecutive case series ascertained through multiple sources in a defined geographical area. The association appears to be confined to certain families, and affective disorder may appear as long as 20 years before the onset of chorea and dementia. The association may represent genetic heterogeneity in HD.