Studies of the Neanderthal and Denisovan genomes demonstrate archaic hominin introgression in Eurasians. Here, we present evidence of Neanderthal introgression within the chromosome 3p21.31 region, occurring with a high frequency in East Asians (ranging from 49.4% to 66.5%) and at a low frequency in Europeans. We also detected a signal of strong positive selection in this region only in East Asians. Our data indicate that likely candidate targets of selection include rs12488302-T and its associated alleles--among which four are nonsynonymous, including rs35455589-G in HYAL2, a gene related to the cellular response to ultraviolet-B irradiation. Furthermore, suggestive evidence supports latitude-dependent selection, implicating a role of ultraviolet-B. Interestingly, the distribution of rs35455589-G suggests that this allele was lost during the exodus of ancestors of modern Eurasians from Africa and reintroduced to Eurasians from Neanderthals.
Keywords: East Asians; HYAL; Neanderthals; introgression; positive selection.