Fine scale human genetic structure in three regions of Cameroon reveals episodic diversifying selection
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Date
2021
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nature research /scientific reports
Abstract
Inferences from genetic association studies rely largely on the defnition and description of the underlying populations that highlight their genetic similarities and diferences. The clustering of human populations into subgroups (population structure) can signifcantly confound disease associations. This study investigated the fne-scale genetic structure within Cameroon that may underlie disparities observed with Cameroonian ethnicities in malaria genome-wide association studies in sub-Saharan Africa. Genotype data of 1073 individuals from three regions and three ethnic groups in Cameroon were analyzed using measures of genetic proximity to ascertain fne-scale genetic structure.
Model-based clustering revealed distinct ancestral proportions among the Bantu, Semi Bantu and Foulbe ethnic groups, while haplotype-based coancestry estimation revealed possible longstanding and ongoing sympatric diferentiation among individuals of the Foulbe ethnic group, and their Bantu and Semi-Bantu counterparts. A genome scan found strong selection signatures in the HLA gene region, confrming longstanding knowledge of natural selection on this genomic region in African populations following immense disease pressure. Signatures of selection were also observed in the HBB gene cluster, a genomic region known to be under strong balancing selection in sub-Saharan
Africa due to its co-evolution with malaria. This study further supports the role of evolution in shaping genomes of Cameroonian populations and reveals fne-scale hierarchical structure among and within Cameroonian ethnicities that may impact genetic association studies in the country.
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https://doi.org/10.1038/s41598-020-79124-1