Alpha1-antitrypsin deficiency is a genetic model that predisposes to pulmonary emphysema or a form of hepatic cirrhosis in man. The antitrypsin protein protects the tissues from proteolytic digestion by lysosomal proteases from inflammatory cells. The three causes of antitrypsin deficiency demonstrated to date are: 1) A defect in synthesis and release of the Z variant from the liver. 2) Presence of an inactive (null) gene for antitrypsin production, and 3) Increased lability of certain variants associated with the in vivo degradation of antitrypsin.