Learn About Alpha-1 Antitrypsin Deficiency

Alpha- antitrypsin deficiency is a rare genetic disorder that is passed on in families and primarily affects the lungs and liver. Rarely, the skin may be affected as well.  When this condition affects the lungs, it causes emphysema, a form of chronic obstructive pulmonary disease.

Key Facts

  • Alpha-1-antitrypsin (AAT) is a protein produced by the liver that protects the lungs from inflammation and damage caused by inhaling irritants such as tobacco or wildfire smoke.
  • It is estimated that there are between 80,000 to 100,000 people living with AAT deficiency in the United States, putting them at greater risk for developing COPD.
  • Alpha-1 lung disease is commonly called ‘genetic COPD’
  • Emphysema caused by AAT deficiency often presents at a younger age
  • There is no cure, but treatment can help people with AAT deficiency manage their symptoms and live a better life.

How AAT Deficiency Affects Your Body

Alpha-1 antitrypsin (AAT) deficiency puts you at greater risk for lung, liver or skin disease. AAT is normally produced in the liver and travels through the blood to protect the lungs and liver from inflammation. AAT deficiency is genetic.  Affected individuals inherit a copy of the abnormal gene from each parent. Generally if you have at least one normal copy of the gene, your AAT levels will be adequate.  There are different types of genetic mutations that can determine the severity of this disease. The lower the level of circulating AAT protein, the greater the risk of disease. 

If you have AAT deficiency and you are exposed to irritants such as smoke, air pollution or dust, your lungs can become more easily damaged. This damage can make it harder to breathe and puts you at greater risk of emphysema, a type of chronic obstructive lung disease (COPD). Not everyone with AAT deficiency develops emphysema, but anyone who has a family member who has AAT deficiency or was diagnosed with COPD in their 40s or 50s should be tested for alpha-1 lung disease. Even if you have one functioning copy of the AAT gene, exposure to lung pollutants like smoke will cause loss of lung function at a greater rate than in persons without the gene mutation. 

AAT deficiency is more likely to affect your liver than your lungs. Untreated, it can result in poor liver function and increase your risk of cirrhosis and liver cancer. In some people, AAT deficiency may cause frequent red, painful nodules on the skin.

Who is at Risk?

AAT deficiency is a genetic (inherited) condition, which means it runs in families. Everyone inherits two AAT genes, one from each parent. If each of your parents pass on a mutated AAT gene, you have AAT deficiency. 

However, if you only receive one mutated AAT gene you become a carrier for AAT deficiency, with a 25% chance of any child you have developing AAT deficiency if your partner is also a carrier. 

AAT deficiency is more common in white people of Northern-European backgrounds, but anyone of any race or ethnicity can inherit it.

People with AAT deficiency are at an increased risk of developing lung disease early in life if they:

  • smoke or use tobacco products
  • are exposed to secondhand smoke
  • work or live in a dusty environment
  • have a family history of emphysema
  • have a personal history of asthma
  • or a history of repeated lung infections.

Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.

Page last updated: October 2, 2023

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