However, mutations within the FOXP3 gene in male infants are causally linked to IPEX (immune dysregulation, polyendocrinopathy, enteropathy, X-linked), a severe perinatal autoimmune syndrome resulting from defects in Treg development and consequent activation of conventional T cells with specificity for self-antigens [18], [19]. Here, FOXP3 is linked to immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome.