Estimates of African, European and Native American Ancestry in Afro-Caribbean Men on the Island of Tobago

Background/Aims: The Tobago Afro-Caribbean population is a valuable resource for studying the genetics of diseases that show significant differences in prevalence between populations of African descent and populations of other ancestries. Empirical confirmation of low European and Native American admixture may help in clarifying the ethnic variation in risk for such diseases. We hypothesize that the degree of European and Native American admixture in the Tobago population is low. Methods: Admixture was estimated in a random sample of 220 men, from a population-based prostate cancer screening survey of 3,082 Tobago males, aged 40 to 79 years. We used a set of six autosomal markers with large allele frequency differences between the major ethnic populations involved in the admixture process, Europeans, Native Americans and West Africans. Results: The ancestral proportions of Tobago population are estimated as 94.0 ± 1.2% African, 4.6 ± 3.4% European and 1.4 ± 3.6% Native American. Conclusions: We conclude that Tobago Afro-Caribbean men are predominantly of West African ancestry, with minimal European and Native American admixture. The Tobago population, thus, may carry a higher burdenof high-risk alleles of African origin for certain diseases than the more admixedAfrican-American population. Conversely, this population may benefit from a higher prevalence of protective alleles of African origin.