FOXP3 and immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome: Genetic analysis has demonstrated that Treg cell dysfunction caused by the FOXP3 mutation is responsible for the immune dysregulation polyendocrinopathy enteropathy X-linked syndrome [IPEX, also called X-linked autoimmunity–allergic dysregulation syndrome (XLAAD)], a recessive immune disorder occurring in newborns and children (74).