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Common variable immunodeficiency (acquired or adult-onset hypogammaglobulinemia) is characterized by low immunoglobulin (Ig) levels with phenotypically normal B cells that can proliferate but do not develop into Ig-producing cells.
Common variable immunodeficiency (CVID) includes several different molecular defects, but in most patients, the molecular defect is unknown. CVID is clinically similar to X-linked agammaglobulinemia in the types of infections that develop, but onset tends to be later, even in adulthood. T-cell immunity may be impaired in some patients. Autoimmune disorders (eg, SLE, Addison's disease, thyroiditis, RA, alopecia areata, autoimmune thrombocytopenia, autoimmune hemolytic or pernicious anemia) can occur, as can malabsorption, nodular lymphoid hyperplasia of the GI tract, lymphoid interstitial pneumonia, splenomegaly, and bronchiectasis. Gastric carcinoma and lymphoma occur in 10% of patients.
Diagnosis
Diagnosis is suggested by familial clustering of autoimmune disorders and is confirmed by measuring serum Ig and antibody titers to protein and polysaccharide vaccine antigens. If either measurement is low, B-cell quantification by flow cytometry is indicated to distinguish CVID from X-linked agammaglobulinemia, multiple myeloma, and chronic lymphocytic leukemia. Serum protein electrophoresis is indicated to screen for monoclonal gammopathies (eg, myeloma), which may be associated with reduced levels of other Ig isotypes. If patients are treated with IV immune globulin (IVIG) before testing, serologic tests have no value because the antibodies are from the IVIG.
Treatment
Treatment consists of IVIG 400 mg/kg once/mo and antibiotics as needed to treat infection. Rituximab or a corticosteroid may be required to treat autoimmune disorders.
Last full review/revision September 2008 by Rebecca H. Buckley, MD
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