AATD is a genetic disorder leading to emphysema and chronic obstructive pulmonary disease mostly due to a significantly low level of AAT (47); the concentration of circulating AAT is 20–53 μM in normal individuals while it ranges from 3 to 7 μM in AATD individuals with homozygous Z genotype (5). Here, SERPINA1 is linked to alpha 1-antitrypsin deficiency.