SERPINA1 and alpha 1-antitrypsin deficiency: Misfolding and polymerization of mutant AAT (zAAT) predisposes AATD patients to hepatic cirrhosis and impairs secretion of AAT into the circulation, resulting in protease-antiprotease imbalance in the lung, degradation of elastin by excess neutrophil elastase activity over time, and early-onset panacinar emphysema.