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Alpha 1 Anti-Trypsin Deficiency
(AAT Deficiency; Alpha-1 Antiprotease Deficiency)
Pronounced: Al-fa-wun An-tee-TRIP-sin Dee-FISH-en-see
by Alexandra Howson, PhD
Alpha 1 anti-trypsin (AAT) deficiency is a rare genetic disorder that causes the enzyme AAT to not work well. It can cause lung and liver disease in children and adults.
AAT deficiency is an inherited disorder. 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 of your parents have the gene for AAT deficiency, you are at risk of developing problems due to the disease. If both your parents carry the gene, you are at higher risk of having severe problems.
The first symptoms of the disease often appear in adulthood between the ages of 20-50 years:
In addition, if the liver is affected in adults, the following symptoms may be present:
Symptoms in children can occur in the first weeks of life or later in childhood.
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 bodily fluids and tissues may be tested. This can be done with:
Images may be taken of your lungs. This can be done with a chest x-ray.
Talk with your doctor about the best treatment plan for you. Treatment options include the following:
Treatment for Lung Disease
You may be prescribed medications to boost the levels of AAT. These may be given weekly through an IV in your arm. If you have emphysema, your doctor may treat you with inhaled steroids and other medications to improve your breathing.
If you smoke, your doctor will work with on ways to quit. Smoking can increase the damage to your lungs.
You cannot prevent AAT deficiency if you have inherited the condition. If you have AAT deficiency, you can reduce your chance of emphysema:
Canadian Liver Foundation
The Lung Association
Alpha-1 antitrypsin deficiency. National Jewish Health website. Available at:
...(Click grey area to select URL)
Accessed March 9, 2016.
Alpha-1 antitrypsin deficiency. The Merck Manual Professional Edition website. Available at:
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Accessed June 2014. Accessed March 9, 2016.
Alpha-1 anti-trypsin deficiency (AAT). EBSCO DynaMed Plus website. Available at: http://www.dynamed.... Updated August 5, 2015. Accessed March 9, 2016.
Hericks AJ. An overview of alpha-1 antitrypsin deficiency. Mo Med. 2007;104(3): 255-259.
Last reviewed March 2017 by EBSCO Medical Review BoardMichael Woods, MD
Last Updated: 6/20/2013
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