Comprehensive immunological workup showed panhypogammaglobulinemia (IgG 262 mg/dL, IgM 42 mg/dL, IgA 7 mg/dL), lymphopenia (1170 cells/μL), reduced absolute B cells (20 cells/μL, 1.4% of lymphocytes), and decreased percentages of naïve CD4 T cells (10% of CD3+CD4+). The gene discussed is CD4; the disease is lymphopenia.