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Selective IgA Deficiency
Primary Immunodeficiency

By Vincent Iannelli, M.D., About.com Guide

About.com Health's Disease and Condition content is reviewed by the Medical Review Board

Approximately one out of every 600 people have selective IgA deficiency. Among those with this PI, people of European ancestry greatly outnumber those of other ethnic groups. People with this deficiency lack immunoglobulin A (IgA), a type of antibody that protects against infections of the mucous membranes lining the mouth, airways, and digestive tract.

What causes IgA deficiency?

IgA deficiency is caused by faulty white blood cells called B cells or B lymphocytes. While patients have normal numbers of B cells, these cells do not mature into normal IgA-producing cells. Scientists do not know the exact cause or causes for these immature B cells. Sometimes clusters of cases occur in families. People with IgA-deficiency are more likely than the general population to be related to someone with combined variable immunodeficiency, another form of immune deficiency. Researchers are trying to find the genes that cause IgA deficiency on the involved chromosomes.

What are the symptoms of IgA deficiency?

Many people with IgA-deficiency are healthy, with no more than the usual number of infections. Those who do have symptoms typically have recurring ear, sinus, or lung infections that may not respond to regular treatment with antibiotics. People with IgA-deficiency are likely to have other problems, including allergies, asthma, chronic diarrhea, and autoimmune diseases.

How is IgA deficiency diagnosed?

People with IgA deficiency have low levels of IgA antibodies in their blood. In contrast, their levels of IgM and IgG usually are normal. IgA-deficient people also have normal levels of immune system cells, including T cells and phagocytes, and complement proteins.

Doctors diagnose IgA deficiency by doing tests to measure the amount of total Ig in the blood as well as the type of Ig known as IgG2. Other tests determine how well a person is producing antibodies against specific germs following immunization with a common vaccine, such as a tetanus shot.

How is IgA deficiency treated?

There is no specific treatment for selective IgA deficiency. Doctors treat bacterial infections with antibiotics. They give patients with giardiasis (an infection caused by a common intestinal parasite) metronidazole or quinacrine hydrochloride.

For More Information:

reproduced from the National Institute of Allergy and Infectious Diseases Fact Sheet on Primary Immune Deficiency
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