Selective deficiency of IgA is the most common immune deficiency disorder. Persons with this disorder have low or absent blood levels of a special protein called immunoglobulin A.

IgA deficiency is inherited, which means it's passed down through families. It may be inherited as an autosomal dominant or autosomal recessive trait. It is found in approximately 1 in 700 individuals of European origin. It is less common in people of other ethnicities.

See also: Celiac disease - sprue

Most people with selective IgA deficiency have no symptoms.

Some people with this condition have chronic diarrhea caused by intestinal infections. Some have frequent ear, sinus, and lung infections.

Other symptoms include mouth infections and unexplained asthma or bronchiectasis (a disease in which the small air sacs in the lungs become damaged and enlarge).

There may be a family history of IgA deficiency. Tests that may be done include:

• IgG subclass measurements
• Quantitative immunoglobulins
• Serum immunoelectrophoresis

No specific treatment is available. Some people gradually develop normal levels of IgA without treatment.

Individual infections should be treated with appropriate antibiotics. In some cases, longer courses of antibiotics may be needed to prevent infections from coming back.

Those with selective IgA deficiency who also have IgG subclass deficiencies benefit from immunogloulin (IVIG) treatments given through a vein.

Autoimmune disease treatment is based on the specific problem.

NOTE: People without any IgA may develop anti-IgA antibodies if given blood products and IVIG. This may lead to allergies or life-threatening anaphylactic shock. These individuals can safely be given IgA-depleted IVIG.

Selective IgA deficiency is less harmful than many other immunodeficiency diseases.

Some people with IgA deficiency will recover on their own and begin to produce IgA in larger quantities over a period of years.

An autoimmune disorder, such as rheumatoid arthritis and systemic lupus erythematosus, and celiac sprue may develop.

Patients with IgA deficiency may develop antibodies to IgA, and can have severe, even life-threatening reactions to transfusions of blood and blood products. If transfusions are necessary, washed cells may be cautiously given.

Consider genetic counseling if there is a family history of selective IgA deficiency and you plan to have children.

If you have an IgA deficiency, be sure to mention it to the provider if IVIG or other blood-component transfusions are suggested as a treatment for any condition.

Genetic counseling may be of value to prospective parents with a family history of selective IgA deficiency.

Azar AE. Evaluation of the adult with suspected immunodeficiency. Am J Med. 2007; 120(9):764-8.

Hoffman R, Benz EJ, Shattil SS, et al. Hematology: Basic Principles and Practice. 4th ed. Orlando, Fl: Churchill Livingstone; 2005.

Mandell GL, Bennett JE, Dolin R. Principles and Practice of Infectious Diseases. 6th ed. London: Churchill Livingstone; 2005.

Morimoto Y. Immunodeficiency Overview. Prim Care. 2008; 35(1):159-7, viii.