Although IPEX syndrome has not been reported, carriers display a bimodal FOXP3 expression within the CD4+CD25+CD127low T-cell population for FOXP3 mutations that do not affect Treg-cell development (e.g., c.1150G>A) (72). This evidence concerns the gene FOXP3 and immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome.