FOXP3 and immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome: For example, genetic deficiency of forkhead box p3 (FOXP3), a key transcription factor involved in Treg differentiation and functional specification, leads to the systemic autoimmune disorder, immune dysregulation polyendocrinopathy enteropathy X-linked syndrome (IPEX) in humans (3) and scurfy in mice (4, 5).