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.