Overview of Alpha-1 Antitrypsin Deficiency-Mediated Liver Disease

Abstract

Alpha-1 antitrypsin (AAT), encoded by the SERPINA1 gene, is a protein mainly produced and secreted by hepatocytes. Some specific mutations affecting SERPINA1 may cause accumulation of misfolded AAT in the endoplasmic reticulum of the hepatocytes leading to AAT deficiency (AATD). Z-AAT is the most severe and common deficient variant. This mutant is not only retained in the endoplasmic reticulum but accumulates as an aggregate that triggers a cascade of intracellular signalling pathways inducing hepatocyte injury and death. Nevertheless, among all the homozygous ZZ patients only 15% develop liver injury, with a wide-range of disease severities ranging from hepatic fibrosis to cirrhosis or even hepatocellular carcinoma. Due to the lack of knowledge surrounding modifiers associated with Z-AAT-mediated hepatocyte toxicity, it is impossible to screen for AATD patients at risk of liver damage and to develop accurate therapeutic strategies. This review aims to give an overview and update our knowledge of AATD associated with liver disease and discusses possible new therapeutic strategies.