Noteworthy, HAA and VAA proved to be valuable markers of IPEX syndrome also in atypical cases, such as Pt24, where enteropathy was not part of the clinical presentation, dominated instead by a severe gastritis, in whom IPEX was suspected and then confirmed by FOXP3 gene sequencing only after the finding of elevated HAA. Here, FOXP3 is linked to immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome.