Given the role of mucins in forming a barrier against infection in the respiratory tract, the high MUC20 expression in ciliated epithelial cells from the bronchus52 and the detection of the MUC20 eQTL in pulmonary tissue (Supplementary Note 11), we suggest that the greater resistance to infection conferred by the Neanderthal haplotype may result from a similar effect on MUC20 expression in the respiratory tract. The gene discussed is MUC20; the disease is infection.