Selective deficiency of IgA is defined as low levels of or complete absence of immune globulin A, which causes decreased immune function in the mucosal surfaces (e.g., mouth, gastrointestinal tract, and lungs) and results in increased risk for respiratory and gastrointestinal infections. It is associated with autoimmune diseases.
Causes, incidence, and risk factors
IgA deficiency may be inherited as either an autosomal dominant (requiring only one parent to pass down the defective gene) or recessive (requiring defective genes from both) trait and is found in approximately 1 in 700 individuals of European origin. It is less common in people of other ethnicities.
Affected people often have chronic diarrhea caused by intestinal infections, frequent respiratory infections. Many develop autoimmune diseases like rheumatoid arthritis and lupus erythematosus.
- family history of IgA deficiency
- family history of agammaglobulinemia (Bruton agammaglobulinemia)
- mouth infections
- frequent respiratory infections
- unexplained asthma and/or bronchiectasis
Signs and tests
- Serum immunoelectrophoresis
- Quantitative immunoglobulins (serum IgA extremely low or absent)
No specific treatment is available for IgA deficiency. However, transfusion of IV Ig (intravenous immune globulin) can be harmful. Some people gradually develop normal levels of IgA without treatment. Individual infections should be treated with appropriate antibiotics. Autoimmune disease treatment is based on the specific problem.
Selective IgA deficiency is more benign than many other immunodeficiency diseases.
Some people with IgA deficiency will recover spontaneously and begin to produce IgA in larger quantities over a period of years. People with a complete absence of IgA may develop allergies or anaphylactic shock if given gamma globulin.
An autoimmune disorder may also develop. Patients with IgA deficiency may develop antibodies to IgA, and can have severe reactions (including anaphylaxis, a potentially life-threatening allergic reaction) to transfusions of blood and blood products. If transfusions are necessary, they should ideally come from another IgA-deficient individual.
Calling your health care provider
Consider genetic counseling if there is a family history of selective IgA deficiency and children are planned.
If you have an IgA deficiency, be sure to mention it to the provider if gamma globulin is suggested as a treatment for any condition.
Genetic counseling may be of value to prospective parents with a family history of selective IgA deficiency.
by Janet G. Derge, M.D.