Most patients were diagnosed with CVID (10/16 patients, one of whom due to NFKB2 deficiency), four patients with X-linked agammaglobulinemia (XLA), one patient with immunodeficiency due to Kabuki syndrome and one with Hyper-IgM syndrome of unknown origin. The gene discussed is NFKB2; the disease is hyperinsulinemic hypoglycemia, familial, 4.