title: Ethnic differences in the expression of neurodegenerative disease: Machado-Joseph disease in Africans and Caucasians.
abstract: 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. Haplotype analysis shows that these African families do not share a common founder, thus a cis-acting element in the promoter is unlikely to be responsible these unusual presentations. We suggest that trans-acting factors are responsible for the variable phenotype and discuss the implications of diseases showing racially different expressivities.
mesh_terms: D001741:Black or African American / Q000706:statistics & numerical data; D017668:Age of Onset; D005006:Ethnicity / Q000706:statistics & numerical data*; D015870:Gene Expression / Q000235:genetics*; D005819:Genetic Markers; D006801:Humans; D017827:Machado-Joseph Disease / Q000453:epidemiology* / Q000235:genetics*; D010641:Phenotype; D018911:Trinucleotide Repeats / Q000235:genetics; D044465:White People / Q000706:statistics & numerical data
chemical_list: D005819:Genetic Markers