This is a glycoprotein produced in the liver which is the major antiprotease in the blood, serving mainly to inhibit leukocyte elastase. It is a single-chain molecule, has 394 amino acids and a molecular weight of 51,000. Hereditary antitrypsin deficiency is one of the most common genetic disorders among males of European descent. Alpha-1-antitrypsin deficiency results in leukocyte elastase building up and breaking down the lining of the lung, which results in a severe form of emphysema (oxidizing agents in cigarette smoke are also known to inactivate antitrypsin, thus causing the high rates of emphysema among long-term smokers). Because over 20,000 people are affected by this deficiency, large amounts of this antiprotease are needed. To meet the demand, researchers are genetically engineering sheep that produce the antiprotease in their milk.