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selective IgA deficiency

Etiology: 1) pharmaceutical agents reported to cause IgA deficiency a) phenytoin b) carbamazepine c) penicillamine d) hydroxychloroquine e) sulfasalazine f) sodium aurothiomalate Epidemiology: 1) most common immunoglobulin deficiency 2) found in approximately 1/600 healthy subjects Pathology: 1) frequently associated with IgG subclass IgG2 & IgG4 deficiency (may be risk factor for severe infection) 2) most patients have normal levels of circulating B-cells which fail to differentiate into plasma cells secreting IgA 3) pulmonary disease is common & often severe 4) infections are most frequently caused by encapsulated organisms 5) decreased antibody response to carbohydrate antigens such as pneumococcal vaccine 5) bronchiectasis & obstructive airway disease occur in 40% of patients 6) patients may make IgE anti-IgA Genetics: - associated with defects in TNFRSF13B (type2), also seen with common variable immunodeficiency Clinical manifestations: - most patients are asymptomatic or minimally symptomatic - recurrent sinopulmonary infections due to Streptococcus pneumoniae &/or Haemophilus influenzae - diarrhea, malabsorption or gastrointestinal infections (giardiasis) may occur - autoimmune disease may also occur [2] - atopic dermatitis - urticaria - asthma Laboratory: 1) serum IgA < 5-7 mg/dL (normal 70-300 mg/dL) 2) normal serum IgG & serum IgM Complications: 1) greater prevalence of: a) allergy, especially food allergy b) autoimmune diseases 1] rheumatoid arthritis 2] systemic lupus erythematosus 3] autoimmune hemolytic anemia 4] immune thrombocytopenic purpura (ITP) [2] 5] hypothyroidism 6] vitiligo 7] celiac disease c) maligancies 1] gastric adenocarcinoma 2] lymphoma d) gastrointestinal infections - giardiasis 2) anaphylactoid reactions have occurred when IgA-deficient patients are given blood transfusions or IgG preparations containing small amounts of IgA (IgE anti-IgA) Management: - not an indication for intravenous immunoglobulin, except for patients who are also deficient in IgG2 or IgG4 (monitor closely) - caution with blood transfusions - fresh-frozen plasma is the main blood component containing IgA - IgA-deficient donor may be option - washing erythrocytes & platelets can decrease incidence of anaphylaxis [2,4] - no specific measures except preventive measures against known complications - as needed antibiotics for recurrent sinopulmonary infections [2] - pneumococcal vaccination

Related

common variable immunodeficiency (CVID) immunoglobulin-A (IgA)

General

humoral immune dysfunction

Database Correlations

OMIM 609529

References

  1. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 747
  2. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, 16, 17, 18, 19. American College of Physicians, Philadelphia 1998, 2006, 2009, 2012, 2015, 2018, 2021. - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  3. Yel L. Selective IgA deficiency. J Clin Immunol. 2010 Jan;30(1):10-6 PMID: 20101521
  4. Sandler SG. How I manage patients suspected of having had an IgA anaphylactic transfusion reaction. Transfusion. 2006 Jan;46(1):10-3. PMID: 16398725
  5. Singh K, Chang C, Gershwin ME. IgA deficiency and autoimmunity. Autoimmun Rev. 2014 Feb;13(2):163-77. Review. PMID: 24157629