ATG16L1 and inflammatory bowel disease: Autophagic genes, such as ATG16L1, ATG4, ULK1, nucleotide-binding oligomerization domain 2 (NOD2) and nuclear receptor binding factor 2 (NRBF2), have all been involved in IBD regulation; in particular, ATG16L1 and NOD2 mutations were identified to be causative of IBD in a genome-wide association study (GWAS) of IBD [13,14].