Genetic variation in ATG16L1 (autophagy related 16 like 1), and specifically the missense variant rs:41880 Thr300Ala (T300A), impairs autophagy in cell models, provides risk for developing CD [9–11], and predisposes to ileal disease [12] and a complicated disease course [13]. The gene discussed is ATG16L1; the disease is Cowden disease.