The intracellular functional marker Helios, encoded by the IKZF2 gene, was also lower in APS-1 patients’ cells compared to controls (frequencies mean patients 14.3%, mean controls 27.3%, p = 0.0016; geometric mean (mean patients 575.6, mean controls 804.0, p = 0.0143, Figure 4C). The gene discussed is IKZF2; the disease is autoimmune polyendocrine syndrome type 1.