Employing this classical assay for defining the kinetics of AAT protein processing and secretion, we utilized an AATD iPSC line in which both mutant Z alleles had undergone zinc-finger-mediated gene correction, comparing the corrected clone to its parental, syngeneic PiZZ line (Yusa et al., 2011). Here, SERPINA1 is linked to alpha 1-antitrypsin deficiency.