AAT deficiency

AAT deficiency


Alpha-1 antitrypsin deficiency is a lack of a liver protein that blocks the destructive effects of certain enzymes. The condition may lead to emphysema and liver disease

Alternative Names

AAT deficiency


Alpha-1 antitrypsin deficiency results from a genetic defect. The mechanism that causes associated liver disease and emphysema in some people with this deficiency is not known. However, some evidence suggests that it may be related to inflammation.

Studies now show that Alpha-1 antitrypsin deficiency may be more common than once thought. Approximately 75% of adults with severe deficiency will develop emphysema, which often begins before 40 years of age. Smoking can increase the risk.


  • Shortness of breath with and without exertion
  • Unintentional weight loss
  • Wheezing
Additional symptoms that may be associated with emphysema or cirrhosis include the following:
  • Abnormal breathing pattern (exhalation takes more than twice as long as inspiration)
  • Agitation
  • Ankle, feet, and leg swelling
  • Awakening from sleep not feeling rested
  • Bloody, dark black, or tarry bowel movements (melena)
  • Breast development in males
  • Confusion
  • Daytime sleepiness
  • Difficulty falling asleep or staying asleep (insomnia)
  • Difficulty paying attention
  • Dry mouth
  • Excessive thirst
  • Fatigue
  • Fluctuating mood
  • Headache
  • Impaired concentration
  • Impaired judgment
  • Impotence
  • Increased front-to-back diameter of the chest (barrel-shaped chest)
  • Irritability or poor temper control
  • Light-headedness or fainting while standing
  • Memory loss
  • Paleness
  • Rapid heart rate when rising to a standing position
  • Skin rash or lesion on the hands or feet, redness
  • Slow, sluggish, lethargic movement
  • Swollen abdomen or increased girth
  • Vision abnormalities
  • Vomiting blood
  • Vomiting material that looks like coffee grounds

Exams and Tests

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

  • Arterial blood gases
  • Serum alpha-1 antitrypsin level
  • Chest x-ray
  • Pulmonary function test
  • Genetic testing


Replacement (augmentation) therapy with the missing AAT protein is available. However, it is not known how effective this is once disease has developed or which people would benefit most. Quitting smoking is crucial.

Other treatments include bronchodilators and prompt antibiotics for upper respiratory tract infections. Lung transplantation may be an option for those who develop end-stage lung disease. In addition, genetic testing of relatives may be recommended.

Outlook (Prognosis)

Some people with this deficiency will not develop liver or lung disease. Emphysema and cirrhosis, however, are both progressive diseases that can kill.

Possible Complications

  • Emphysema
  • Cirrhosis

When to Contact a Medical Professional

Call your health care provider if you develop symptoms of alpha-1 antitrypsin deficiency.

Perlmutter, DH. Alpha-1-antitrypsin deficiency: diagnosis and treatment. Clin Liver Dis. November 2004;8:839-859.

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.

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