Alpha-1 Antitrypsin (AAT) Deficiency is a genetic disorder characterised by the production in the liver of an abnormal AAT protein. The liver cells cannot secrete this abnormal AAT protein, which accumulates within the cells and results in a marked reduction of circulating AAT levels. Although the mechanisms are not completely known, it is believed that the retained abnormal AAT protein over time leads to liver injury in some affected persons. In the lungs low-levels of AAT allow for the destructive effects of neutrophil elastase to go unchecked. This results in damage to the delicate gas exchange region of the lungs (alveoli), eventually leading to emphysema in people as young as 30 years of age. Thus, people with AAT Deficiency are at high risk of developing life-threatening liver and lung disease.