Ethnic differences in the expression of neurodegenerative disease: Machado-Joseph disease in Africans and Caucasians.

We describe several families of African origin with SCA3/Machado-Joseph disease gene expansions. In these cases, the phenotype ranges from ataxia with parkinsonian signs to a syndrome clinically almost indistinguishable from idiopathic, L-dopa-responsive Parkinson's disease. In contrast, these parkinsonian phenotypes are rare in those of European descent.