IRGM and inflammatory bowel disease: Although the cause of IBD is still unclear, there is a possibility that a hereditary predisposition in humans, such as NOD2/CARD15, IRGM, and ATG16L1, may be relevant to the onset of IBD (Watanabe et al., 2004; Massery and Parkes, 2007; Henckaerts et al., 2008).