ATG16L1 and Cowden disease: It is surprising that we did not see a gut microbiota shift related to genotype in our rat model when differences exist in predisease patients with CD with the Atg16l1 susceptibility variant; however; many disparities between human and rat host factors exist, such as diet, environment, and features of the gastrointestinal system itself (differences in small intestine: colon ratios, size of the cecum, etc.)which could explain why the rat gut microbiota may be less susceptible to changes based on the T300A variant alone.