In detail, high serum IgA (392 mg/dL) and a mild IgG2 subclass deficiency (25 mg/dL) were detected, with increased IgE (208 UI/mL) and adequate specific antibody response to pneumococcus (pneumococcal antibody 39.55 mg/dL, protective from 7 mg/dL). This evidence concerns the gene IGHE and hyperinsulinemic hypoglycemia, familial, 4.