Huntington's disease in black kindreds in South Carolina.

Since the first report in 1890 of hereditary chorea in a black family, there have been few epidemiologic references to Huntington's disease (HD) in blacks and, to our knowledge, no estimates of the prevalence of HD in blacks in the Unites States. On Jan 1, 1980, the estimated minimum prevalence of HD in blacks in South Carolina was 0.97 per 100,000 persons, about one fifth the prevalence for white patients with HD in South Carolina. However, detailed studies of eight newly reported cases of HD from four black kindreds indicate that the mean age of onset (41.75 +/- 4.33 years) and clinical course resemble those of white patients with HD in South Carolina. We comment on possible roots of this prevalence difference between whites and blacks with HD.