AAT, also known as SERPINA1; serpin peptidase inhibitor, clade A (alpha-1 antiproteinase, antitrypsin), member 1. It is secreted and is a serine protease inhibitor whose targets include elastase, plasmin, thrombin, trypsin, chymotrypsin, and plasminogen activator. Severe Serpin A1 deficiency leads to several clinical complications such as pulmonary emphysema, juvenile hepatisis, cirrhosis and hepatocellular carcinoma.