The confirmation of FOXP3 function derives from a recent discover: a mutation of the FOXP3 gene may lead to a pediatric syndrome characterized by the association of several different autoimmune diseases (IPEX Syndrome: immune dysfunction, poliendocrinopathy, enteropathy, and X-linked) [9]. The gene discussed is FOXP3; the disease is immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome.