The abnormal distributions of T and B lymphocytes may mimic a late-onset combined immune-deficiency (LOCID) phenotype, with upper respiratory tract and pulmonary bacterial infections (hypogammaglobulinemia, fewer B lymphocytes, especially switched memory B lymphocytes), and opportunistic infections (fewer CD4+ T lymphocytes, especially naïve CD4+). The gene discussed is CD4; the disease is Opportunistic infection.