ATG16L1 and Cowden disease: Considering the abnormal expression of CEACAM6 in the ileal epithelium of CD patients and its role as receptor for ileal AIEC [19], we also analyzed for a potential association with an ileal CD phenotype and investigated potential gene-gene interactions with the NOD2 gene, which has been shown to be a strong predictor of ileal CD, as well as with other CD susceptibility genes such as IL23R and ATG16L1.