FOXP3 and immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome: Because half of the patients, whose phenotype suggested IPEX, did not have a mutation in FOXP3, we investigated if these two groups could be differentiated phenotypically by comparing clinical and laboratory data of patients with FOXP3 mutations (IPEX, n = 88) to those lacking an identifiable FOXP3 mutation (IPEX-like, n = 85).