Less common IEI included Wiskott-Aldrich syndrome (WAS, 3%, 6 cases), hyper Immunoglobulin M syndrome (HIM, 1.5%, 3 cases), Griscelli syndrome, Hyper Immunoglobulin E syndrome (HIES), Hemophagocytic lymphohistiocytosis (HLH), Adenosine Deaminase 2 Deficiency (DADA2), Idiopathic CD4 lymphocytopenia (ICL), and PIK3R1 mutation (each with 0.5% or 1 case). The gene discussed is ADA2; the disease is hyperinsulinemic hypoglycemia, familial, 4.