These A20-Atg16l1ΔIEC mice develop spontaneous IBD-like pathology characterized by severe inflammation in both small and large intestine, crypt abscesses with marked epithelial cell death, Paneth cell loss, and villi erosion, in contrast to single A20ΔIEC or Atg16l1ΔIEC mice, which do not develop overt intestinal abnormalities nor inflammation in homeostatic conditions. The gene discussed is TNFAIP3; the disease is inflammatory bowel disease.