Alpha 1 Anti-Trypsin Deficiency

(AAT Deficiency; Alpha-1 Antiprotease Deficiency)

Pronounced: Al-fa-wun An-tee-TRIP-sin Dee-FISH-en-see


Alpha 1 anti-trypsin (AAT) deficiency is a rare genetic problem that causes the enzyme AAT to not work well. It can cause lung and liver disease in children and adults.

Causes    TOP

AAT deficiency is inherited. It is passed from parents to children. This condition occurs when the liver does not make useful AAT. AAT is a protein that protects the lungs and other organs from damage. When functional AAT levels are too low, lung damage may occur.

People with AAT deficiency can also develop liver disease. AAT deficiency is one of the major causes of genetic liver disease in children. The liver makes an abnormal version of AAT protein that builds up in the liver. This blockage can damage liver cells. In some cases, severe liver damage can occur.

Risk Factors    TOP

If either parent has the gene for AAT deficiency, their child is at risk of developing problems due to the disease. If both parents carry the gene, their child is at higher risk of having severe problems.

Symptoms    TOP

The first symptoms of the disease often appear in adulthood between the ages of 20-50 years:

  • Shortness of breath during mild activity
  • Coughing up sputum (mucus from deep in the lungs)
  • Wheezing
  • Weight loss
  • Lung disease that affects the air sacs
  • Raised red spots on the skin

If the liver is affected in adults, the following symptoms may be present:

  • Itching
  • Yellowing of the skin and/or whites of the eyes
  • Vomiting
  • Swollen abdomen
  • Abdominal pain

Symptoms in children can occur in the first weeks of life or later in childhood.

  • Infants:
    • Yellowing of the skin and/or whites of the eyes
    • Poor growth and weight gain
    • Foul-smelling stools
    • Swollen abdomen
    • Vomiting
    • Itching
  • Older children:
    • Fatigue
    • Poor appetite
    • Swollen abdomen

Diagnosis    TOP

You will be asked about your symptoms and medical history. A physical exam will be done. You may be referred to a doctor who specializes in the lungs or liver, depending on the symptoms you are having.

Your body's fluids and tissues may be tested. This can be done with:

  • Blood tests—to examine if AAT levels in the blood are low
  • Genetic testing—to identify the inherited change that causes AAT
  • Liver biopsy —a small piece of the liver is removed and examined for inflammation or scarring

Images may be taken of your lungs. This can be done with a chest x-ray.

Liver Biopsy

Placement of Liver Biopsy Needle
Copyright © Nucleus Medical Media, Inc.

Treatment    TOP

Talk with your doctor about the best treatment plan for you. Treatment options include the following:

Treatment for Lung Disease


Medications may be prescribed to boost the levels of AAT. These may be given weekly through an IV in the arm. The doctor may treat people with emphysema with inhaled steroids and other medications to improve breathing.

Smoking Cessation

Smoking can increase the damage to your lungs. The doctor can suggest smoking cessation strategies.

Treatment for Liver Damage

There is no specific treatment for liver disease due to AAT deficiency. Treatment focuses on symptoms and preventing complications. Treatment may include:

  • Vitamin supplements, such as E, D, and K
  • Medications to reduce itching and jaundice
  • Rarely, a liver transplant

Prevention    TOP

You cannot prevent AAT deficiency if you have inherited the condition. If you have AAT deficiency, you can reduce your chance of emphysema:

  • Quit smoking.
  • Avoid exposure to secondhand smoke.
  • Avoid exposure to air pollution or irritants.
  • Wear protective gear if exposed to irritants or toxins at work.


Alpha-1 Association
American Lung Association


Canadian Liver Foundation
The Lung Association


Alpha-1 antitrypsin deficiency. National Jewish Health website. Available at:
...(Click grey area to select URL)
Accessed March 19, 2018.
Alpha-1 antitrypsin deficiency. The Merck Manual Professional Edition website. Available at:
...(Click grey area to select URL)
Accessed January 2017. Accessed March 19, 2018.
Alpha-1 anti-trypsin deficiency (AAT). EBSCO DynaMed Plus website. Available at: http://www.dynamed... . Updated January 19, 2018. Accessed March 19, 2018.
Hericks AJ. An overview of alpha-1 antitrypsin deficiency. Mo Med. 2007;104(3): 255-259.
Last reviewed March 2018 by EBSCO Medical Review Board Kari Kassir, MD
Last Updated: 6/20/2013

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