SERPINA1 and alpha 1-antitrypsin deficiency: For example, previous work from our group and others shows that liver organoids derived from Pi*ZZ AATD patients mimic the main liver features, are, namely, positive for PAS (Periodic acid-Schiff) diastase-resistant staining, contain intracellular Z-AAT polymers, and show reduced secretion of AAT into extracellular medium [17].