FOXP3 and immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome: An example is a polyadenylation signal mutation (AAUAAA → AAUGAA) in the FOXP3 (forkhead box P3) gene causing the IPEX syndrome, which is characterized by immune dysfunction, polyendocrinopathy and enteropathy (Bennett & Ochs, 2001).