Antitrypsin Deficiency is a genetic disorder that affects the lungs and liver. It is caused by a deficiency of the protein alpha-1 antitrypsin (AAT), which is produced in the liver and helps protect the lungs from damage. People with Antitrypsin Deficiency are at an increased risk of developing lung diseases such as emphysema and chronic obstructive pulmonary disease (COPD). They may also be at risk of developing liver disease. Treatment for Antitrypsin Deficiency includes lifestyle changes, medications, and in some cases, a liver transplant.