Alpha-1 Antitrypsin Deficiency Genetic Testing

What Is Alpha-1 Antitrypsin Deficiency?

Alpha-1 antitrypsin (AAT) is a protein normally found in the lungs and the bloodstream. It helps protect the lungs from diseases such as emphysema and chronic obstructive pulmonary disease (COPD). People who do not make enough of this protein-this is called AAT deficiency-are more likely to have these lung diseases and will get them at a younger-than-normal age (30 to 40 years old). It can also damage the liver. AAT deficiency is a rare disorder and is the only known genetic (inherited) factor that increases your chances for having lung diseases.

Alpha-1 antitrypsin deficiency is caused by a change, or mutation, in the gene that tells the body how to make alpha-1 antitrypsin. There are many kinds of possible changes in this gene, but only a few cause problems. To have this condition, you have to get the changed gene from both parents.

If you receive only one changed gene, you have the changed gene but not the disease (you are a carrier ). The good copy of the gene you received from your other parent is enough to tell your body how to properly make alpha-1 antitrypsin. Some people who carry the changed gene may have very mild symptoms of the deficiency.

Treatment for alpha-1 antitrypsin deficiency mainly involves avoiding substances-especially cigarette smoke-that could harm your lungs. Also try to avoid dust and workplace chemicals. You also may want to avoid alcohol because of the risk of liver damage. Exercise can improve your stamina and overall health.

The only treatment available for the lack of the protein is plasma containing alpha-1 antitrypsin. This is usually given only to people who have very low levels of AAT in their blood. It is not clear that this treatment is any better than avoiding smoke and other lung-damaging chemicals. The plasma is made from the blood of many donors and it is treated to reduce the chance of spreading an infectious disease. You receive the plasma through an IV, usually every 3 to 4 weeks for life.

What Is AAT Deficiency Testing?

A blood test can measure the amount of alpha-1 antitrypsin (AAT) in your blood. You may have AAT deficiency if your levels are low or if the blood test is not able to find any AAT in your blood. If your AAT level is lower than normal, the blood sample can be tested to look for the type of alpha-1 antitrypsin. People who carry the changed gene may be more at risk for symptoms if they have a certain type of alpha-1 antitrypsin.

Is Testing Accurate?

Although this blood test is highly reliable, no test is 100% accurate. This test cannot predict when-or whether-you will develop symptoms or how severe they will be.

Should I Be Tested?

The decision to have the test is personal. You may have emotional, financial, and family reasons for taking or not taking the test.

You may choose to have the test because:

• You have unexplained lung problems and want to know whether you have this condition.
• Other people in your family have AAT deficiency.
• Other people in your family have unexplained lung disease or liver disease.
• You want to take steps to protect your health if you find out you have the condition.
• You would be relieved to know that you do not have the changed gene.
• You would change your decision about having children because of test results.
• Your insurance would pay for the test.

Why Would I Not Be Tested?

You may decide not to be tested because:

• You do not have symptoms of lung disease.
• No one in your family has AAT deficiency or lung or liver disease.
• You would be worried if you knew that you might get lung or liver disease some day.
• You do not smoke and you already are taking good care of yourself. You think there is nothing more you could do to prevent or delay the disease.
• The test cannot predict whether you will ever have symptoms of this condition.
• You do not have insurance or your insurance would not pay for the test.
• You are worried that the test results might cause problems for you at work or make it hard for you to get health insurance.

What Is Genetic Counseling?

Information from genetic testing can have a big impact on your life. Ask to have genetic counseling before making a decision about testing. Genetic counselors are trained to explain the test and its results, but you make the decision about whether to have the test. A genetic counselor can help you make well-informed decisions. Genetic counseling can help you and your family:

• Understand medical facts, including what causes diseases, how a diagnosis is made, and what you may be able to do to help you manage a disease.
• Understand how your family history contributes to the development of a disease.
• Help you learn about caring for a family member with a genetic disease, including getting referrals to specialists or joining support groups.

Genetic counselors are trained to help you and your family make informed decisions. They are sensitive to the physical and emotional aspects of these decisions. Your privacy and confidentiality are carefully protected.

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References

Other Works Consulted

• Pagana KD, Pagana TJ (2006). Mosby's Manual of Diagnostic and Laboratory Tests, 3rd ed. St. Louis: Mosby.

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