What causes alpha-1 antitrypsin deficiency (Alpha-1)?

What causes alpha-1 antitrypsin deficiency (Alpha-1)?

Mutations (changes) in the gene that produces the AAT protein cause Alpha-1. In people with the most common abnormal type of Alpha-1 (called ZZ type), AAT proteins are misshapen. These proteins can’t pass from the liver into the bloodstream, so the number of AAT proteins in the blood is low and the amount of AAT in the liver cells is increased.

When people have low AAT levels in the bloodstream, there isn’t enough AAT protein to protect the lungs and other organs from the effects of infection or irritants. Low levels of AAT can cause conditions such as emphysema and bronchitis (inflammation of the linings of the lungs). Your risk of developing lung problems with Alpha-1 increases a lot if you smoke.

Additionally, when AAT is unable to move out of the liver, it can build up and cause damage and scarring to the liver cells. This damage can lead to disorders such as cirrhosis and liver cancer.

Alpha-1 is a genetic condition, meaning a parent passes it to a child. Severe forms of the condition develop in people who get the abnormal gene from both parents. People who get an abnormal gene from just one parent are carriers, meaning they can pass the gene to their children. They also have a small risk of developing lung disease, especially if they smoke, and of liver disease.