Alpha-1 antitrypsin deficiency

Alternative names
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.

Causes, incidence, and risk factors
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. Approximately 75% of adults with severe deficiency will develop emphysema, which often begins before 40 years of age. Smoking can increase risk.


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 or 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

Signs 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


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. Certainly, quitting Smoking is crucial.

Other treatments include bronchodilators and prompt antibiotics for upper respiratory tract infections.

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


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

Johns Hopkins patient information

Last revised: December 5, 2012
by David A. Scott, M.D.

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