Tal Klatchko, D.O.

Pulmonary & Critical Care
Roper-St. Francis Hospital
Charleston, South Carolina

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.


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.


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.


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.

Risk Group

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.

Signs and Symptoms

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 (Shortness of breath, Wheezing, Decreased ability to do physical activity.) at age 45 years or younger.


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

  • A genetic test – This test will show whether you have altered AAT genes.
  • A blood test – This test checks the levels of AAT protein in your blood.
  • A Pulmonary function tests – These tests show how well you’re able to blow air out of your lungs.


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.

  • 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.