The study included five patients with X-linked agammaglobulinemia (XLA), four patients with Ataxia Telangiectasia (AT), and eight patients with various combined immunodeficiency (CID) diseases; STAT3 deficiency, CD40 ligand deficiency and IL6 receptor deficiency. The gene discussed is STAT3; the disease is hyperinsulinemic hypoglycemia, familial, 4.