Absence of functional Foxp3 protein due to mutations in the Foxp3 gene  results in the development of severe autoimmune disorders as can be observed in the “scurfy” mouse mutant [14] and patients suffering from immune dysregulation, polyendocrinopathy, enteropathy, and X-linked syndrome (IPEX) [15]. Here, FOXP3 is linked to immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome.