The <i>MUC19</i> gene: An evolutionary history of recurrent introgression and natural selection.

Abstract

We study the gene <i>MUC19</i>, for which some modern humans carry a Denisovan-like haplotype. <i>MUC19</i> is a mucin, a glycoprotein that forms gels with various biological functions. We find diagnostic variants for the Denisovan-like <i>MUC19</i> haplotype at high frequencies in admixed American individuals and at highest frequency in 23 ancient Indigenous American individuals, all pre-dating population admixture with Europeans and Africans. We find that the Denisovan-like <i>MUC19</i> haplotype is under positive selection and carries a higher copy number of a 30-base-pair variable number tandem repeat, and that copy numbers of this repeat are exceedingly high in admixed American populations. Finally, we find that some Neanderthals carry the Denisovan-like <i>MUC19</i> haplotype, and that it was likely introgressed into modern human populations through Neanderthal introgression rather than Denisovan introgression.