Genome-Wide Search for Signatures of Natural Selection in African Americans

Abstract

The several genomic regions showing excess of African or European ancestry could be the footprints of natural selection in the post-admixture era. In order to detect the natural selection since the African or European ancestry left for the New World, we reconstructed an artificial African population using the inferred African ancestral chromosomal segments and compared it with indigenous African populations. Interestingly, many selection-candidate genes identified by the later approach were associated with African American specific high-risk diseases such as prostate cancer and hypertension, suggesting these disease-related genes might have played an important role in African Americans adapting to the new environment. CD36 and HBB, whose mutations confer a degree of protection against malaria, were also located in those highly differentiated regions between the artificial African population and indigenous African population. Further analysis showed frequencies of alleles protecting against malaria were lower in artificial African population than in indigenous African population, which consists with the relaxed selection pressure of malaria in U.S.