The genetics of IBD were recognized by genome-wide association studies (GWAS) showing that people harboring variants in innate and adaptive immunity-related genes were more susceptible to both ulcerative colitis (UC) and CD, such as nucleotide-binding oligomerization domain-containing protein 2 (Nod2), immunity-related GTPase family protein M (IRGM), autophagy-related protein 16 like protein 1 (Atg16l1), interleukin 12B (IL-12B), Drosophila mothers against decapentaplegic protein 3 (SMAD3), and others (15–17). The gene discussed is NOD2; the disease is ulcerative colitis.