NOD2 and inflammatory bowel disease: IBD is considered as a polygenic disease, with the exception of rare monogenic cases.17 The notable example of research into the genetic basis of IBD is the introduction of NOD2 as the first CD susceptibility gene.18 To date, the continued search for genetic determinants of IBD identified 242 variants associated with IBD,17 of which 45 have been fine mapped to statistically significant causal variants.