Runs of homozygosity in sub-Saharan African populations provide insights into complex demographic histories.

The study of runs of homozygosity (ROH) can shed light on population demographic history and cultural practices. We present a fine-scale ROH analysis of 1679 individuals from 28 sub-Saharan African (SSA) populations along with 1384 individuals from 17 worldwide populations. Using high-density SNP coverage, we could accurately identify ROH > 300 kb using PLINK software. The genomic distribution of ROH was analysed through the identification of ROH islands and regions of heterozygosity (RHZ). The analyses showed a heterogeneous distribution of autozygosity across SSA, revealing complex demographic histories. They highlight differences between African groups and can differentiate the impact of consanguineous practices (e.g. among the Somali) from endogamy (e.g. among several Khoe and San groups). Homozygosity cold and hotspots were shown to harbour multiple protein coding genes. Studying ROH therefore not only sheds light on population history, but can also be used to study genetic variation related to adaptation and potentially to the health of extant populations.