Deficiency in FoxP3 due to genetic mutations results in a lethal X-linked recessive lymphoproliferative disease in mice and human subjects characterized by immunodysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome.21 This autoimmune disorder is characterized by a severe intestinal pathology, with massive T-cell infiltration, type 1 diabetes mellitus, eczema, anemia, liver infiltration, thrombocytopenia, hypothyroidism, and the presence of various autoantibodies. Here, FOXP3 is linked to autoimmune disease.