Among the IPEX-like cohort, patients with mutations in genes related to Treg function (i.e., CD25, STAT5b, STAT3 and STAT1 GOF, LRBA, CTLA4) are affected by a clinical phenotype strongly resembling IPEX. This evidence concerns the gene STAT5B and immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome.