Apolipoprotein e polymorphism in elderly East Africans

Abstract

Current advances have shown the apolipoprotein E (APOE)-£4 allele to be highly associated with late-onset familial and sporadic Alzheimer's disease (AD) in Western populations. The association of A POE allele frequencies and dementia remain unknown in populations from developing countries. We recently initiated a project to examine APOE frequencies in non¬demented and demented elderly East Africans. Blood DNA collected from two hospital¬based populations showed that the A POE allele frequencies in a group of non-demented 67 Tanzanians over the age of 65 years were found to be 14% for £2, 61 % for £3 and 25% for £4. By comparison, the frequency ofAPOE-£4 in an age-matched demented group was also 25 O/C. Assessment of APOE genotypes in the group of elderly Kenyan subjects from Nairobi also revealed high frequencies of the £4 allele with no clear difference in frequency between demented and non-demented subjects. Our preliminary observations suggest that elderly East Africans with no apparent clinical AD possess relatively high APOE-£4 allele frequencies compared to normal ageing subjects from Western countries including African-Americans. These results appear similar to those reported in a recent study in Nigerian Africans where a lack of correlation between APOE-£4 allele frequency and Alzheimer type of dementia was noted, and imply thatA POE-£4 allele may not necessarily be a risk factor in some populations of Africa.