Diagnoses included common variable immunodeficiency (n=25), specific antibody deficiency (n=9), ataxia-telangiectasia (n=5), X-linked agammaglobulinemia (n=4), PIK3CD-related disorders (n=4), hyper-IgM syndrome (n=4), combined immunodeficiency (n=3), and STAT1 gain-of-function (n=1). The gene discussed is STAT1; the disease is isolated agammaglobulinemia.