Based on the common pathway theory, the shared AFgenes with influenza (CCL2, IL18, IL1B, IL6, MX1, NFKB1, RAF1, STAT1, TMPRSS2, and TNF), RA (CCL2, IL18, IL1B, IL6, MMP3, TGFB1, and TNF), and IBD (IL10, IL18, IL1B, IL6, NFKB1, NOD2, STAT1, STAT3, TGFB1, and TNF) may serve as entry points for future research on disease comorbidity mechanisms. The gene discussed is IL18; the disease is inflammatory bowel disease.