African Americans are at higher risk for cardiometabolic disease relative to individuals with European ancestry. Yet, populations with African ancestry are greatly under-represented in human genomics studies. To alleviate this bias and better distinguish the roles of genetics and environment on cardiometabolic traits, we conducted targeted metabolomics to measure levels of >700 lipids in 718 Africans and integrated with genomic data from >7M single nucleotide polymorphisms genotyped in the same individuals. These individuals are from 14 ethnic groups from diverse regions of Africa (Botswana, Cameroon, Ethiopia, Tanzania) and with diverse subsistence patterns (agriculturalists, pastoralists, hunter-gatherers). In contrast to US populations, most individuals were sampled from rural areas with relatively homogenous diets and, thus, we could better quantify lipids typically found at low levels in US individuals. Furthermore, several groups have similar genetic ancestry but distinct diets, and vice versa, enabling us to distinguish the role of genetic ancestry and environment on lipid variation. We identified 305 independent genetic variants associated with 103 lipid species, >50 of which have not previously been reported in similar studies of European/US populations (e.g. at ROCK2, ARHGEF28, DHODH, ALDH1A2). We observe correlations between subsistence and lipid profiles but show that genetic ancestry also plays an important role in variation within and between populations. For example, Eastern African pastoralists with a diet rich in milk and blood have relatively high levels of di-and tri-glycerides, but within each lipid class, levels are influenced by genotype. The Fulani pastoralists from Cameroon, with a high incidence of hypertension and diabetes but low BMI, also have relatively high levels of triglycerides, suggesting diet is predominantly influencing lipid levels and that genetic factors unrelated to lipid metabolism are influencing risk for disease in that population.
R. Ma: None. H. Li: Consultant; Self; Eli Lilly and Company. C. Burant: None. S. A. Tishkoff: None. M. Hansen: None. A. Ranciaro: None. S. R. Thompson: None. W. Beggs: None. S. W. Mpoloka: None. G. G. Mokone: None. T. B. Nyambo: None. G. Michailidis: None.
American Diabetes Association (1-19-VSN-02 to S.A.T.); National Institutes of Health (GM134957-01)