Immunoglobulin A Deficiency

Deficiency of immunoglobulin A (IgA) is the most common primary immunodeficiency. It is characterized by very low to absent levels of IgA in the bloodstream. This can result in frequent infections that involve mucous membranes, such as in the ears, sinuses, lungs, and gastrointestinal tract.

People with IgA deficiency are at an increased risk of other conditions, including certain autoimmune diseases, gastrointestinal (GI) diseases, allergic diseases, and worsening forms of immunodeficiency.

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What Is IgA?

IgA is the most abundant antibody produced by the body. It is present in the bloodstream and it is secreted on the surface of mucous membranes.

The most important role of IgA is to protect against infections from the numerous bacteria that are present on the mucous membranes.

What Is IgA Deficiency?

Slightly low IgA values are not consistent with IgA deficiency.

For a diagnosis of IgA deficiency, a person must have:

  • Complete absence or extremely low values of IgA measured in the blood
  • Normal IgG and IgM levels

IgA deficiency is thought to be inherited in approximately 20% of new cases, and the cause of this deficiency is not known in most cases.

What Are the Symptoms of IgA Deficiency?

It is not understood why some people have many complications from this antibody deficiency and some don't have any effects. Most people who have IgA deficiency don't experience any increase in infections whatsoever. Some, but not all, people with IgA deficiency are at an increased risk for infections that involve the mucous membranes,

Clinical effects can include an increase in:

  • Sinusitis
  • Middle ear infections (otitis media)
  • Lung infections, including pneumonia
  • GI tract infections, such as Giardiasis

Gastrointestinal Conditions

IgA deficiency is also associated with other GI diseases, including celiac disease and ulcerative colitis.

Celiac disease is most commonly diagnosed by the presence of IgA antibodies against certain proteins in the GI tract—but this would not found in a person who has both celiac disease and IgA deficiency. Instead, IgG antibodies against these same proteins would be expected to be present in a person with celiac disease.

If you have possible celiac disease, you might also have a test to check for IgA deficiency. This can help determine whether a normal test for celiac disease could actually be a false negative result as a consequence of IgA deficiency.

Blood Transfusion

Some people with severe IgA deficiency actually make allergic antibodies (IgE) against IgA antibodies. Blood transfusions generally contain IgA antibodies, so a severe IgA allergy could increase the risk for anaphylaxis as a result of receiving blood transfusions.

If an emergency blood transfusion is necessary, a blood product with few IgA antibodies may be used to minimize the chance of anaphylaxis. Therefore, if you have severe IgA deficiency, you might be advised to wear a medical alert bracelet to ensure a safer blood transfusion if you need one.

Comorbidities

IgA deficiency is associated with an increased risk for comorbidities. These include various autoimmune diseases, including certain blood diseases (such as ITP), rheumatoid arthritis, systemic lupus erythematosus, and Graves' Disease. These diseases occur in approximately 20-30% of people with IgA deficiency.

Complications

GI cancers and lymphomas can occur at higher rates in people with GI disorders associated with IgA deficiency.

These cancers are thought to be due to increased inflammation in the GI tract and they are not thought to be increased if people are asymptomatic or do not have GI manifestations of IgA deficiency.

Some people with IgA deficiency may progress to worsening forms of immunodeficiency, such as common variable immunodeficiency (CVID).

What Is the Treatment for IgA Deficiency?

The main treatment for IgA deficiency is the treatment of infections or of the associated diseases that may occur. If you have IgA deficiency and recurring infections, you should be treated earlier and more intensively than someone without IgA deficiency. This can include treatment with antibiotics for bacterial infections.

You should have immunizations against common infections, such as the seasonal influenza vaccine and the pneumococcal vaccine. And you need to avoid live vaccines if you have a severe IgA deficiency.

If you have IgA deficiency, your healthcare provider will monitor you for signs of autoimmune diseases, GI diseases, allergic conditions, and worsening immunodeficiency.

DISCLAIMER: The information contained in this site is for educational purposes only, and should not be used as a substitute for personal care by a licensed practitioner. Please see your healthcare provider for diagnosis and treatment of any concerning symptoms or medical condition.

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1 Source
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  1. Immune Deficiency Foundation. Selective IgA Deficiency.

Additional Reading
  • Yel L. Selective IgA Deficiency. J Clin Immunol. 2010;30:10-16.