FOXP3 and Abnormal intestine morphology: Additionally, mutations in Foxp3 can lead to severe food allergies and the development of two severe autoimmune syndromes: XLAAD (X-linked autoimmunity-allergic dysregulation syndrome) and IPEX (immunodysregulation, polyendocrinopathy, enteropathy, X-linked syndrome) in which oral tolerance is abrogated (32, 33).