NFKB1 and inflammatory bowel disease: As can be seen in Fig. 2, this analysis revealed two large distinct gene clusters: Cluster 1 includes multiple known IBD causal genes including IFIH1, SBNO2, NFKB1, and NOD2, with several candidate genes connecting to them, while Cluster 2 has multiple candidate genes connecting to the IBD causal gene KSR1.