High total IgE levels, eosinophilia and atopic symptoms may also be associated with other IEI, including Omenn Syndrome, Wiskott-Aldrich syndrome, WIP deficiency, ARPC1B deficiency, IPEX syndrome, STAT5b deficiency, STK4 deficiency, MALT1 deficiency, IL21 deficiency, and Di-George syndrome making the diagnosis of HIES more difficult (14). Here, IL21 is linked to hyperinsulinemic hypoglycemia, familial, 4.