Health Encyclopedia

Alpha-1 antitrypsin deficiency

Definition

Alpha-1 antitrypsin (AAT) deficiency is condition passed down through families in which the liver does not make enough of a protein that protects the lungs and liver from damage. The condition can lead to emphysema and liver disease.

Alternative Names

AAT deficiency

Causes, incidence, and risk factors

Alpha-1 antitrypsin (AAT) is a type of protein called a "protease inhibitor." AAT normally works to protect the lungs from a naturally occuring destructive enzyme that is produced by the lungs in response to infections and toxins (such as cigarette smoke). Without enough AAT, these enzymes slowly destroy the lung tissue.

AAT deficiency is caused by a genetic defect that results in not enough AAT in the liver, lungs, and blood. Persons with this deficiency may also develop liver disease.

Studies show that AAT deficiency may be more common than once thought. Most adults with severe deficiency will develop emphysema, which often begins before age 40. Smoking can increase your risk. The condition is most common among Europeans and North Americans of European descent.

Symptoms

Shortness of breath with and without exertion, and other symptoms of chronic obstructive pulmonary disease (COPD)
Symptoms of cirrhosis
Unintentional weight loss
Wheezing

Signs and tests

A physical examination may reveal a barrel-shaped chest. Listening to the chest with a stethoscope may reveal wheezing or decreased breath sounds. The following tests may also help with diagnosis:

Alpha-1 antitrypsin blood test
Arterial blood gases
Chest x-ray
CT scan of the chest
Genetic testing
Pulmonary function test

Your doctor may suspected you having this condition if you develop:

Emphysema before age 45
Emphysema but have never smoked or been exposed to toxins
Liver disease or hepatitis and no other cause can be found

Treatment

Treatment involves replacing the missing AAT protein. The protein is given through a vein each week. However, it is not yet known who may benefit from such therapy.

Quitting smoking is crucial.

Other treatments specifically for emphysema and cirrhosis are also used.

Expectations (prognosis)

Some people with this deficiency will not develop liver or lung disease. However, emphysema and cirrhosis can be deadly.

Complications

Cirrhosis or liver failure
Emphysema
Liver cancer

Calling your health care provider

Call your health care provider if you develop symptoms of AAT deficiency.

References

Köhnlein T, Welte T. Alpha-1 antitrypsin deficiency: pathogenesis, clinical presentation, diagnosis, and treatment. JAMA. 2008;121(1):3-9.

Stoller JK, Tomashefski J, Crystal RG, et al. Mortality in individuals with severe deficiency of alpha-1-antitrypsin: Findings from the National Heart, Lung, and Blood Institute Registry. Chest. April 2005;127:1196-1204.

Review Date:8/29/2008
Reviewed By:Sean O. Stitham, MD, private practice in Internal Medicine, Seattle, WA; Benjamin Medoff, MD, Assistant Professor of Medicine, Harvard Medical School, Pulmonary and Critical Care Unit, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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