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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 problem that causes the enzyme AAT to not work well. It can cause lung and liver disease in children and adults.
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.
The first symptoms of the disease often appear in adulthood between the ages of 20-50 years:
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 body's 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
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 can increase the damage to your lungs. The doctor can suggest smoking cessation strategies.
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 19, 2018.
Alpha-1 antitrypsin deficiency. The Merck Manual Professional Edition website. Available at:
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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 BoardKari Kassir, MD
Last Updated: 6/20/2013
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