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Author: Esther Forrester, MD
IgA deficiency is the most common primary immunodeficiency, with an occurrence ranging from 1/400 to 2,000 individuals. The frequency of IgA deficiency is greater in people of European descent and may be as high as 1 in 500. In the United States, whites are affected more than blacks by a ratio of 20:1. Asian Americans have an even lower incidence, with the occurrence in Japanese descendents being 1 in 18,500 persons.
IgA deficiency may be primary or secondary (acquired), sporadic, or familial. Both serum and secretory IgA are lacking in most patients and, rarely, one or the other is lacking. Inheritance is either autosomal recessive or dominant. The primary defect in selective IgA deficiency is related to a failure of B cells to differentiate in response to appropriate stimuli to mature isotype-switched surface IgA-positive B cells and IgA-secreting plasma cells.Thebasisfor thedefectis notknown. Certaindrugs,such asphenytoin, D-penicillamine, sulfasalazine, and hydroxychloroquine, have been associated with this entity. Congenital cases of noninherited IgA deficiency in association with rubella, cytomegalovirus, and Toxoplasma gondii have been reported.
Although some studies have reported recurrent infections in as many as 50% of IgA-deficient patients, most of these individuals are healthy. Some patients develop symptoms after an uneventful childhood and early adulthood. Recurrent or chronic upper and lower respiratory tract infections result in bronchiectasis or cor pulmonale in insufficiently treated patients. Gastrointestinal infection with Giardia lamblia infection is common as are a spruelike syndrome, ulcerative colitis, and Crohn disease.
The incidence of autoimmune and collagen vascular diseases, including rheumatoid arthritis, systemic lupus erythematosus, autoimmune hepatitis, hemolytic anemia, and endocrinopathies, is also increased, with reports of up to 25% of patients being affected.
PatientswithundetectablelevelsofIgAantibodiesmaydevelopanti-IgA antibodies after the administration of blood products. Once sensitized, these patients are at risk for anaphylactic reactions if they receive blood products containing even small amounts of IgA. An antibody response to cow's milk protein is also common.
The variability in clinical expression is explained by several factors. Symptoms may be attenuated by an increased excretion of monomeric IgM in these patients' secretions, which helps to compensate for the lack of IgA. Symptoms maybeworsened by the association ofan IgG subclass deficiency.
Intravenous Ig (IVIG) replacement therapy is the treatment of choice for most primary B-cell disorders with hypogammaglobulinemia, including x-linked agammaglobulinemia, common variable immunodeficiency, immunodeficiency with thymoma, and most of the combined immunodeficiencies. However, selective IgA deficiency has no treatment. Therapy should be directed toward the specific disease. Administration of IVIG to patients with IgG subclass deficiency is not recommended unless antibodies are absent or there is no response to prophylactic antibiotics. Gammaglobulin is not used in selective IgA deficiency unless IgG2 subclass deficiency or antibody deficiencyisalsopresent.Theprognosisisthesameastheassociateddisorder.
Cooper MA, Pommering TL, Korī
anyi K. Primary immunodeficiencies. Am Fam Physician.
2003;68:2001–2008.
Makhoul I, Claxton D, Rybka W. Pure B-cell Disorders. Available at: www.emedicine.com/
med/topic216.htm. Accessed March 2, 2007.
National Primary Immunodeficiency Resource Center. Selective IgA Deficiency. Available at:
http://www.info4pi.org/faq/index.cfm?Section=faq&CFID=24824785&CFTOKEN=
51564784#24. Accessed March 1, 2007.
Read excerpts from these other book chapters related to Hypoglycemia:
Copyright Details: Avoiding Common Pediatric Errors, Copyright © 2008 Williams & Wilkins.
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More About This Book:
Title: Avoiding Common Pediatric Errors Authors: Anthony D Slonim MD, DrPH; Lisa Marcucci MD Publisher: Lippincott Williams & Wilkins Copyright: 2008 ISBN: 0-7817-7489-6 
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