Dysfunctional 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 and patients suffering from immune dysregulation, polyendocrinopathy, enteropathy, and X-linked syndrome (IPEX) (24, 25). Here, FOXP3 is linked to polyendocrinopathy.