NOD2 and inflammatory bowel disease: NOD2, as an important gene involved in regulating inflammation and autophagy(Fritz et al. 2011; Mukherjee et al. 2019; Negroni et al. 2018), was the first susceptibility gene discovered to be associated with IBD (Branquinho et al. 2016; Goethel et al. 2019; Venkataraman and Rivas 2019).