in situ proteomic analysis (combining laser microdissection of hepatocytes and mass spectrometry analysis) on formalin-fixed paraffin-embedded (FFPE) human liver tissues of 4 ZZ-Alpha 1-Antitrypsin Deficiency (AATD) pediatric patients and 4 ZZ-AATD adult patients that underwent liver transplantation versus 3 WT individuals infants and 4 adults, and compared proteins differentially expressed in ZZ pediatric and in ZZ adult AATD patients.