What Is Alpha-1 Antitrypsin Deficiency?
Alpha-1 antitrypsin (an-tee-TRIP-sin) 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 (em-fi-SE-ma)—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 (sir-RO-sis) 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
(pa-NIK-yu-LI-tis). 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 lifespan. 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:
- Shortness of breath
- Wheezing (a whistling or squeaky sound when you
breathe)
- Decreased ability to do physical activity
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 (lung specialists), and hepatologists
(liver specialists).
To check whether the disease you have may be related
to AAT deficiency, your doctor will:
- Ask about possible risk factors. A common sign of
AAT deficiency is when you have a lung or liver disease without any obvious
causes or risk factors. Another is if you have
emphysema at an unusually early age (45 years or
younger).
- Ask about your family's medical history. If you
have close family members who have AAT deficiency, you're more likely to have
the condition.
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:
- Medicines called inhaled bronchodilators
(brong-ko-di-LA-tors) that help open your airways and make breathing easier.
These medicines also are used to treat
asthma
and
chronic
obstructive pulmonary disease.
- Flu and pneumococcus (noo-mo-KOK-us) vaccines to
protect you from diseases that could make your condition worse.
- Pulmonary rehabilitation (rehab). This involves
treatment by a team of experts at a special clinic. In rehab, you learn how to
manage your condition and function at your best.
- Extra oxygen if needed.
- A lung transplant. You may need a transplant if
your lung is so badly damaged that it severely affects your breathing. If you
have a good chance of surviving the transplant surgery, you may be a candidate
for it.
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 (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.
- Quit smoking. If you're not a smoker, don't
start.
- Avoid secondhand smoke and places with dust,
fumes, or other toxic substances that you may inhale.
- Check your living and working spaces for things
that may irritate your lungs. Examples include flower and tree pollen, ash,
allergens, air pollution, wood burning stoves, paint fumes, and fumes from
cleaning products and other household items.
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. (For more information, see "How Is Alpha-1
Antitrypsin Deficiency Treated?")
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:
- Quit or don't start smoking. Smoking is the
leading risk factor for lung disease.
- Avoid secondhand smoke and places where you might
inhale dust, fumes, or other toxins.
- Check your living and working spaces for things
that may irritate your lungs. Examples include flower and tree pollen, ash,
allergens, air pollution, wood burning stoves, paint fumes, and fumes from
cleaning products and other household items.
- Advise your children to avoid smoking and to stay
away from places where they might inhale irritants or toxins. Because AAT
deficiency is inherited, your children may have the condition or carry the gene
for it. They should do whatever they can to reduce their risk of getting
serious lung diseases. (Of course, this is true for anyone—with or without
AAT deficiency.)
- Make lifestyle changes to stay healthy, including
following a healthy diet and getting regular physical activity. Talk to your
doctor about how much and what types of physical activity are safe for
you.
- Reduce stress. Relaxation techniques, such as
meditation, yoga, breathing exercises, and muscle relaxation, can help you cope
with stress.
- Talk to your doctor about whether it's safe for
you to drink alcohol.
- Get vaccines to protect you from flu and
pneumococcus. These viruses increase your risk for serious lung diseases.
- Get treatment right away for any breathing
problems. If treatment includes pulmonary rehabilitation, work with your health
care team to learn how to manage your condition and function at your best.
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 AAT deficiency.
Links to Other Information About Alpha-1
Antitrypsin Deficiency
NHLBI Resources
Non-NHLBI Resources
Clinical Trials
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