Further, adaptive immune genes that regulate the interleukin (IL)-17 and IL-23 receptor pathways are implicated in IBD risk, including genes associated with risk for ulcerative colitis and Crohn’s disease (e.g.,IL23R, IL12B, STAT3, JAK2, andTYK2) and those implicated in Crohn’s disease only (e.g.,IL-27, TNFSF15). This evidence concerns the gene IL12B and Crohn disease.