CD4 T-cell lymphopenia was first noted among patients with CVID3–5 and can dramatically reverse the normal CD4:8 ratio when combined with expansion of senescent CD8 T cells, a feature not usually found in other antibody deficiencies.6 Despite the array of observed in vitro T-cell abnormalities, the clinical hallmarks of a T-cell immunodeficiency such as recurrent fungal and viral opportunistic infections are lacking in the majority of patients. The gene discussed is CD4; the disease is agammaglobulinemia.