S100A8 and infection: After confirming the significant association between males and H. pylori infection, we tested which of this bacterium’s genes are sex-linked and found that the presence of the cagA, cagE, and virB11 genes as well as infection by multiple strains are significantly associated with males (p = 0.001, p = 0.003, p =0.014, and p =0.008, respectively, Supplementary Table S6).