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Selective Immunoglobulin Deficiency

by James Fernandez, MD, PhD

Selective immunoglobulin deficiency is usually inherited. It results in a low level of one type (class) of antibody (immunoglobulin), even though the levels of other immunoglobulins are normal.

There are several classes of immunoglobulins, such as immunoglobulin A (IgA), IgD, IgE, IgG, and IgM. Each class helps protect the body from infection in a different way (see Acquired Immunity : Antibodies). The level of any class may be low, but the most commonly affected class is IgA.

Selective IgA deficiency

Selective IgA deficiency is the most common immunoglobulin abnormality. It may be caused by a mutation in a specific gene or by a drug.

Most people with selective IgA deficiency have few or no symptoms. Others develop chronic lung infections, sinusitis, allergies, asthma, nasal polyps, chronic diarrhea, or autoimmune disorders, such as systemic lupus erythematosus (lupus) or inflammatory bowel disease (which usually causes gastrointestinal symptoms that often recur or that may be serious). A few people develop common variable immunodeficiency over time.

If given standard blood transfusions or immune globulin infusions (both of which normally contain IgA), some people with selective IgA deficiency produce antibodies against IgA. These antibodies may trigger a severe allergic (anaphylactic) reaction (see Anaphylactic Reactions) the next time such people are given a blood transfusion or immune globulin. These people should wear a medical identification bracelet or tag to alert doctors to take precautions against such reactions.

Some people improve spontaneously. Life span is usually unaffected. Rarely, an autoimmune disorder or another immune disorder (such as common variable immunodeficiency) develops. These disorders can shorten life span.

Doctors suspect the deficiency in people if they have

  • Recurring infections

  • An anaphylactic reaction to a blood transfusion or to immune globulin

  • Gastrointestinal symptoms that may result from inflammatory bowel disease

  • Family members who have selective IgA deficiency, common variable immunodeficiency, or an autoimmune disorder

Blood tests to measure immunoglobulin levels are done to confirm the diagnosis.

Usually, no treatment of selective IgA deficiency is needed. Antibiotics are given to people who have an infection. If the disorder is severe, antibiotics are given in advance to prevent infections from developing. Selective IgA deficiency that results from taking a drug usually resolves if the drug is stopped.