FOXP3 and immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome: The pivotal roles of Foxp3 in Treg cell function and development are best illustrated by the manifestation of multi-organ autoimmune inflammation in FOXP3-deficient Immunodysregulation Polyendocrinopathy Enteropathy X-linked syndrome (IPEX) patients and Scurfy mice (Bennett et al., 2001; Brunkow et al., 2001; Fontenot et al., 2003).