To date, more than 240 IBD risk genes (e.g. NOD2, CARD9, ATG16L1, IRGM, TNFSF15, GPR65, IL23R, IL12B and TTC7A) have been identified and many of them are involved in the regulation of host-microbiota interactions [10–12]. The gene discussed is NOD2; the disease is inflammatory bowel disease.