title: Letter: On the classification of primary immunodeficiencies.
mesh_terms: D004406:Dysgammaglobulinemia / Q000235:genetics; D006801:Humans; D007111:Immunity, Cellular / Q000145:classification*; D007153:Immunologic Deficiency Syndromes / Q000145:classification* / Q000235:genetics; D013950:Thymus Gland / Q000002:abnormalities