What Is Alpha-1 Antitrypsin Deficiency?



Alpha-1 antitrypsin deficiency, or AAT deficiency, is a condition that raises your risk for certain types of lung disease, especially if you smoke. AAT deficiency is an inherited condition. "Inherited" means it's passed in the genes from parents to children.

Some people who have severe AAT deficiency develop emphysema . . . often when they're only in their forties or fifties. Emphysema is a serious lung disease in which damage to the airways makes it hard to breathe.

A smaller number of people who have AAT deficiency have cirrhosis and other serious liver diseases.

Cirrhosis is a disease in which the liver is scarred. This prevents the liver from working properly. In people who have AAT deficiency, cirrhosis and other liver diseases usually occur in infancy and early childhood.

A very small number of people who have AAT deficiency have a rare type of skin disease called necrotizing panniculitis. This skin disease can cause painful lumps under or on the surface of the skin.

This article will focus on AAT deficiency as it relates to lung disease.

Overview

Alpha-1 antitrypsin, also called AAT, is a protein made in the liver. Normally, the protein goes into the bloodstream and helps protect the body's organs from the harmful effects of other proteins. One of the main organs it protects is the lungs.

AAT deficiency occurs when the AAT proteins made in the liver aren't the right shape. They get stuck inside liver cells and can't get into the bloodstream. Because not enough AAT protein travels to the lungs to protect them, the risk of lung disease increases. Also, because too many AAT proteins are stuck in the liver, liver disease can develop.

AAT deficiency is considered severe when blood levels of the AAT protein fall below the lowest amount needed to protect the lungs.

AAT deficiency is an inherited condition caused by altered genes. It's not known how many people have it. Many people who have it may not know they have it. Estimates of how many people have the condition range from about 1 in every 1,600 people to about 1 in every 5,000 people.

Outlook

You may not have any serious complications if you have AAT deficiency, and you may live a normal life span. Many nonsmokers who have AAT deficiency don't develop any serious related lung diseases.

Among people with AAT deficiency who do have a related lung or liver disease, about 3 percent die each year. Smoking is the leading risk factor for life-threatening lung disease if you have AAT deficiency. If you have severe AAT deficiency, smoking can shorten your life by as much as 20 years.

AAT deficiency has no cure, but there are treatments. In most cases, treatment is based on the type of disease you develop.



What Causes Alpha-1 Antitrypsin Deficiency?

Altered alpha-1 antitrypsin (AAT) genes cause AAT deficiency. AAT genes tell cells in the body how to make AAT proteins.

AAT deficiency occurs when AAT proteins made in the liver aren't the right shape. These proteins get stuck in the liver cells where they are made. They can't get to the organs in the body that they protect, such as the lungs. Without the proteins protecting the organs, diseases can develop.

AAT genes are passed from parents to children. The most common altered AAT gene that can cause AAT deficiency is called PiZ.

If you inherit two PiZ genes . . . one from each of your parents, you will have AAT deficiency. If you inherit a PiZ gene from one parent and a normal AAT gene from the other parent, you will not have AAT deficiency. But, you may pass the PiZ gene to your children.

Even if you inherit two altered AAT genes, you may not have any related complications. You may never even realize that you have this inherited condition.

Who Is At Risk for Alpha-1 Antitrypsin Deficiency?

Populations Affected - In the United States, White people of western and northern European descent are more likely than other ethnic groups to have alpha-1 antitrypsin (AAT) deficiency caused by the PiZ genes. Many altered genes can cause AAT deficiency, but PiZ is the most common.

Major Risk Factors for Alpha-1 Antitrypsin Deficiency - AAT deficiency is an inherited condition. If you have close relatives with known AAT deficiency, you're more likely than others to have this inherited condition. Even so, it doesn't mean that you will have one of the diseases related to the condition.

Some risk factors make it more likely that you will develop lung disease if you have AAT deficiency. Smoking is the leading risk factor for serious lung disease if you have AAT deficiency. Your risk also may go up if you're exposed to dust, fumes, or other toxic substances.

What Are the Signs and Symptoms of Alpha-1 Antitrypsin Deficiency?

You may have alpha-1 antitrypsin (AAT) deficiency if you have signs and symptoms of serious lung disease without any obvious cause. Another sign of AAT deficiency is if you develop emphysema at age 45 years or younger.

Signs and symptoms of emphysema include:

At first, many people who have AAT deficiency are diagnosed with asthma. This is because wheezing is also a symptom of asthma. Also, people who have AAT deficiency respond well to asthma medicines.

How Is Alpha-1 Antitrypsin Deficiency Diagnosed?

Alpha-1 antitrypsin (AAT) deficiency is usually diagnosed after you develop a lung or liver disease that's linked to AAT deficiency.

Because of this, a number of different health care professionals may be involved in the diagnosis of AAT deficiency. These include primary care doctors, pulmonologists . . . are lung specialists, and hepatologists . . . are liver specialists.

To check whether disease you have may be related to AAT deficiency, doctor will:


Diagnostic Tests . . . If your doctor thinks that you have AAT deficiency, he or she may order tests to check for the condition. He or she also may order tests to check for lung- or liver-related conditions.

A genetic test is the most certain way to check for AAT deficiency. This test will show whether you have altered AAT genes.

A blood test also may be used. This test checks the levels of AAT protein in your blood. If the AAT levels are a lot lower than normal, it's likely that you have AAT deficiency.

Lung-Related Tests . . . If you have a lung disease related to AAT deficiency, your doctor may recommend pulmonary function tests and high-resolution computed tomography (CT) scanning.

Pulmonary function tests show how well you're able to blow air out of your lungs. They also show how much air gets into your lungs when you breathe. These tests are used to check how severe your lung disease is and how well treatment is working.

High-resolution CT scanning uses x rays to create detailed pictures of sections of the body. CT scans show whether you have emphysema and how severe it is.



How Is Alpha-1 Antitrypsin Deficiency Treated?

Alpha-1 antitrypsin (AAT) deficiency has no cure. However, the lung diseases linked to this inherited condition have many treatments. Most of these treatments are the same as the ones given to people who have lung diseases without AAT deficiency.

If you have emphysema or other lung diseases or symptoms related to AAT deficiency, your doctor may recommend:

Augmentation therapy is a type of treatment given only to people who have AAT-related lung diseases. This therapy involves getting infusions of the AAT protein. This raises the level of the protein in your blood and lungs.

Not enough research has been done to show whether this type of therapy works. However, some suggest that this therapy may slow the development of AAT deficiency in people who don't have severe disease.

People who have AAT deficiency and develop related liver or skin diseases will be referred to doctors who treat those diseases.

Future Treatments . . . Researchers are working on possible treatments that will target the altered AAT genes and replace them with healthy genes. These treatments are in early stages of development.

If you're interested, talk to your doctor about whether any clinical trials of new AAT treatments might be right for you.

How Can Alpha-1 Antitrypsin Deficiency Be Prevented?

You can't prevent alpha-1 antitrypsin (AAT) deficiency, because the condition is inherited and passed from parents to children. If you inherit two altered AAT genes, you will have AAT deficiency. Even so, you may never have one of the diseases related to the condition.

You can take steps to prevent or delay the lung diseases linked to this condition.

If you have a lung disease related to AAT deficiency, you may want to discuss with your doctor the possibility of getting augmentation therapy. This is a treatment in which you receive infusions of AAT protein. This therapy raises the level of the AAT protein in your blood and lungs.

Living With Alpha-1 Antitrypsin Deficiency

People who have alpha-1 antitrypsin (AAT) deficiency don't always develop serious lung or liver diseases. This means that you can live with AAT deficiency and not even know you have it.

If you do know you have AAT deficiency, you probably also have a related lung or liver disease that requires ongoing medical care.

Some things you can do if you have AAT deficiency are:

If you feel depressed, scared, or upset after being diagnosed with AAT deficiency, talk to your doctor. He or she can recommend support groups or counseling to help you.

Key Points

Alpha-1 antitrypsin (AAT) deficiency is a condition that raises your risk for certain types of lung disease, especially if you smoke. A small number of people who have AAT deficiency develop liver disease and a rare skin disease.

Alpha-1 antitrypsin, also called AAT, is a protein made in the liver. Normally, the protein goes into the bloodstream and helps protect the body's organs from the harmful effects of other proteins. One of the main organs it protects is the lungs.

In AAT deficiency, the AAT proteins made in the liver aren't the right shape. They get stuck inside liver cells and can't get into the bloodstream. This means that the organs don't get enough protection, and the liver has too much AAT protein in it.

AAT deficiency is an inherited condition. "Inherited" means it's passed from parents to children. If you have close relatives with AAT deficiency, you're more likely to have the condition.

You may not have any serious complications if you have AAT deficiency, and you may live a normal lifespan. Many nonsmokers who have AAT deficiency don't develop any serious related lung diseases.

You may have AAT deficiency if you have signs and symptoms of serious lung disease without any obvious cause. Another sign of AAT deficiency is if you develop emphysema at age 45 years or younger.

Your doctor will diagnose AAT deficiency based on your medical and family histories, any risk factors you have, and results from diagnostic tests.

AAT deficiency has no cure. However, the lung diseases linked to this inherited condition have many treatments. These include lifestyle changes, medicines, vaccines, rehabilitation, and surgery.

You can't prevent AAT deficiency, because the condition is inherited. If you inherit two altered AAT genes, you will have AAT deficiency. However, you can take steps to prevent or delay the lung diseases linked to this condition. Quitting smoking and avoiding places with dust, fumes, and other toxic substances are important steps.

Researchers continue to look for new treatments for Alpha-1 antitrypsin deficiency or AAT deficiency.


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