XLA, CVID, CGD, SIgAD, CID, complement deficiency, PAD, X‐linked HIGM, WAS, NEMO deficiency, defects of antigen presentation, ADA deficiency, pulmonary alveolar proteinosis (due to CSF2RA and GATA2 deficiency), AT, NBS, PLAID, reduced serum Ig G2 level. The gene discussed is ADA; the disease is hyperinsulinemic hypoglycemia, familial, 4.