Archaic Hominin Introgression in Africa Contributes to Functional Salivary MUC7 Genetic Variation

Mol Biol Evol. 2017 Oct 1;34(10):2704-2715. doi: 10.1093/molbev/msx206.


One of the most abundant proteins in human saliva, mucin-7, is encoded by the MUC7 gene, which harbors copy number variable subexonic repeats (PTS-repeats) that affect the size and glycosylation potential of this protein. We recently documented the adaptive evolution of MUC7 subexonic copy number variation among primates. Yet, the evolution of MUC7 genetic variation in humans remained unexplored. Here, we found that PTS-repeat copy number variation has evolved recurrently in the human lineage, thereby generating multiple haplotypic backgrounds carrying five or six PTS-repeat copy number alleles. Contrary to previous studies, we found no associations between the copy number of PTS-repeats and protection against asthma. Instead, we revealed a significant association of MUC7 haplotypic variation with the composition of the oral microbiome. Furthermore, based on in-depth simulations, we conclude that a divergent MUC7 haplotype likely originated in an unknown African hominin population and introgressed into ancestors of modern Africans.

Keywords: ABC simulation; CNV; human evolution; microbiome; mucin; recurrent mutation; saliva; structural variation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Alleles
  • Animals
  • Asthma / genetics
  • DNA Copy Number Variations / genetics
  • Evolution, Molecular
  • Exons / genetics
  • Genetic Variation
  • Glycosylation
  • Haplotypes / genetics
  • Hominidae / genetics*
  • Humans
  • Microbiota / genetics
  • Mucins / genetics*
  • Phylogeny
  • Saliva
  • Salivary Proteins and Peptides / genetics*


  • MUC7 protein, human
  • Mucins
  • Salivary Proteins and Peptides