One of the host genetic factors that helps pathobiont selection was reported using genome-wide association studies in IBD, showing polymorphism of 163 loci related to the function of innate immunity and predisposing them to increased risk of inflammatory colitis.15 One such susceptibility gene in Caucasian populations that predisposes them to Crohn’s disease is the nucleotide-binding oligomerization domain 2 (nod2) gene encoding a pathogen-recognition receptor. The gene discussed is NOD2; the disease is Crohn disease.