Alpha-1 Antitrypsin Testing

Why this test may be ordered

• To diagnose or rule out AAT deficiency in people who have symptoms of lung and/or liver disease that may be caused by AAT deficiency
• To screen people who don't have symptoms but have family members with AAT deficiency
• To guide treatment choices for lung disease that may be caused by AAT deficiency

Preparation and collection

You don't need any special preparations for an AAT test.

A health care professional will take a blood sample from a vein in your arm, or from a finger prick. Some genetic tests involve a cheek swab (wiping the inside of your cheek with a small tool). You may have the option of doing the cheek swab yourself.

There is very little physical risk to a blood test. If the blood was taken from your arm, you may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. For a cheek swab, there are no physical risks. There are also emotional and privacy considerations related to genetic testing. You may want to discuss these with a healthcare provider or genetic counselor.

Understanding results

Your test results will be interpreted by your healthcare provider. The following are possible patterns based on the information provided.

• Screen-positive for AAT deficiency: If your AAT blood levels are low, it may mean you have AAT deficiency. To confirm the diagnosis, you'll need a genotype or phenotype test. Limitation: A low AAT blood level alone is not diagnostic; a genotype or phenotype test is needed to confirm AAT deficiency. This result may also be seen in other conditions, so it is not a confirmed diagnosis. Next step: Your provider will likely order a genotype or phenotype test to confirm the diagnosis.
• Screen-negative for AAT deficiency: This suggests that you do not have AAT deficiency, but your provider will interpret the result in the context of your symptoms and other tests. Limitation: A normal AAT level does not completely rule out all forms of AAT deficiency, especially if symptoms are present. Your provider may still recommend genetic testing if there is a strong suspicion. Next step: Your provider will discuss the results with you and may recommend further testing if needed.
• Higher-likelihood of being a carrier of AAT deficiency: You are a carrier of AAT deficiency. This means you are at slightly higher risk of developing lung disease, especially if you smoke or have other risk factors. You can pass the mutated gene to your children. Genetic counseling is recommended. Limitation: Being a carrier means you have one mutated copy of the gene. You are at slightly higher risk of developing lung disease, especially if you have other risk factors such as smoking. This is not a diagnosis of AAT deficiency, and you may not have symptoms. You could pass the mutated gene to your children. Next step: Consider genetic counseling to understand risks for you and your family.
• Higher-likelihood of AAT deficiency (two mutated gene copies): You have a genetic condition that increases your risk for lung disease (such as COPD) and liver disease (such as cirrhosis). Your provider will discuss treatment options and steps to protect your health, such as not smoking. Limitation: Having two mutated copies of the gene indicates a higher-likelihood of AAT deficiency. This result is from genetic testing and should be discussed with your provider. You have a higher risk of lung disease or liver damage, especially before age 45. There is no cure, but treatments can help prevent the condition from getting worse. Next step: Your provider may recommend additional testing to evaluate your lung and liver function. Consider genetic counseling to understand the condition and your risk of passing it to your children.

• A low AAT blood level alone is not diagnostic; a genotype or phenotype test is needed to confirm AAT deficiency.
• A normal AAT level does not completely rule out all forms of AAT deficiency, especially if symptoms are present.
• Genetic testing can identify carriers (people with one mutated copy of the gene) who are at slightly higher risk of developing lung disease, especially if they have other risk factors such as smoking.
• There is no cure for AAT deficiency, but treatments can help prevent the condition from getting worse.

What to do next

If you have questions about your results, talk to your provider. If you are thinking about having AAT testing or have received abnormal results, it may be helpful to speak with a genetic counselor. A genetic counselor can help you understand the risks and benefits of testing for you and your family, and after testing, can help you understand your results and provide information on the condition, including your risk of passing it to your children.

• What do my AAT test results mean for my health?
• Do I need any additional testing to confirm the diagnosis?
• What steps can I take to protect my lungs and liver if I have AAT deficiency?
• Should I consider genetic counseling for myself or my family?

Evidence source

U.S. National Library of Medicine: Alpha-1 Antitrypsin Testing