by EBSCO Medical Review Board
(AAT Deficiency; Alpha-1 Antiprotease Deficiency)


Alpha 1 anti-trypsin (AAT) deficiency is a rare genetic problem. It causes low levels of the protein AAT or stops it from working well. This can lead to lung and liver disease in children and adults.

The Lungs
The Lungs
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AAT is made in the liver. A damaged gene stops the liver from making useful AAT. The faulty gene is passed from parents to children.

Risk Factors

This problem is more common in people of Northern European and Iberian ancestry. It is also more common in people who have a parent who carries the faulty gene. The risk is higher in a person with both parents who carry the gene.


Problems may start at any age, but they often appear in people who are 20 to 50 years of age. They may be:

  • Feeling tired
  • Problems breathing, such as during mild activity
  • Wheezing
  • Coughing up phlegm

AAT that builds up in the liver may cause:

  • Tiredness
  • Lack of hunger
  • Weight loss
  • Swelling in the legs or belly
  • Yellowing of the skin and whites of the eyes
  • Vomiting blood
  • Blood in stools

Rarely, a person may also have skin problems, such as hardened patches or red, painful lumps.


The doctor will ask about your symptoms and health history. A physical exam will be done. This may be enough to suspect the diagnosis. You may be referred to a doctor who treats the lungs or liver.

AAT is diagnosed through these tests:

  • Blood tests to measure AAT levels
  • Genetic testing to find genetic change that causes AAT deficiency


The goal of treatment is to manage symptoms. Options to manage lung problems are:

  • Augmentation therapy to deliver AAT to boost levels
  • Inhaled bronchodilators and steroids to help open the airways and ease breathing
  • Oxygen therapy to boost levels of oxygen in the body
  • Flu and pneumococcal vaccines to lower the risk of lung infections
  • Surgery to remove damaged areas of the lung
  • A lung transplant

People with AAT deficiency should not smoke. They should also avoid being around others who smoke. It can make problems worse.

There are no methods to manage liver problems. Rarely, people with severe liver problems may need a liver transplant.


There are no known guidelines to prevent AAT deficiency.


Alpha-1 Association 

American Lung Association 


Canadian Liver Foundation 

The Lung Association 


Alpha-1 antitrypsin deficiency. National Heart, Lung, and Blood Institute website. Available at: Accessed November 2, 2020.

Alpha-1 antitrypsin deficiency. National Jewish Health website. Available at: Accessed November 2, 2020.

Alpha-1 antitrypsin deficiency. The Merck Manual Professional Edition website. Available at: Accessed November 2, 2020.

Alpha-1 anti-trypsin deficiency (AAT). EBSCO DynaMed website. Available at: Accessed November 2, 2020.

Sandhaus RA, Turino G, et al. The Diagnosis and Management of Alpha-1 Antitrypsin Deficiency in the Adult. Chronic Obstr Pulm Dis. 2016 Jun 6;3(3):668-682.

Revision Information

  • Reviewer: EBSCO Medical Review Board Kari Kassir, MD
  • Update Date: 05/05/2021