CD4 and immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome: These FoxP3+CD4+ Treg cell subsets are non-functional in male scurfy mice and boys with the multi-organ autoimmune disease immune-dysregulation polyendocrinopathy enteropathy X-linked syndrome (IPEX), due to loss-of-function mutations in the X-linked rodent Foxp3 and human FOXP3 genes, respectively.