This case illustrates that a classical pathogenic mutation in <i>FOXP3</i> can lead to a clinical phenotype where the diagnosis of IPEX syndrome was never considered because of the lack of diabetes and the presence of only mild eczema, in addition to the normal Treg cell numbers and FOXP3 expression. This evidence concerns the gene FOXP3 and immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome.