BACKGROUND & AIMS: Alpha-1 antitrypsin deficiency (AATD) is among the most common genetic disorders. Severe AATD is caused by a homozygous mutation in the SERPINA1 gene that encodes the Glu342Lys substitution (called the PiZ mutation, PiZZ genotype). PiZZ carriers may develop lung and liver diseases. Mutation-associated lung disorders have been well studied, but less is known about the effects in liver. We assessed the liver disease burden and associated features in adults with this form of AATD. METHODS: We collected data from 554 PiZZ adults (403 in an exploratory cohort, 151 in a confirmatory cohort), in 9 European countries, with AATD who were homozygous for the PiZ mutation, and 234 adults without the PiZ mutation (controls), all without pre-existing liver disease. We collected data on demographic parameters, comorbidities, lung- and liver-related health, and blood samples for laboratory analysis. Liver fibrosis was assessed non-invasively via the serum tests Aspartate Aminotransferase to Platelet Ratio Index and HepaScore and via transient elastography. Liver steatosis was determined via transient elastography-based controlled attenuation parameter. We performed histologic analyses of livers from transgenic mice that overexpress the AATD-associated PiZ variant. RESULTS: Serum levels of liver enzymes were significantly higher in PiZZ carriers vs controls. Based on non-invasive tests for liver fibrosis, significant fibrosis was suspected in 20%-36% of PiZZ carriers, whereas signs of advanced fibrosis were 9- to 20-fold more common in PiZZ carriers compared to non-carriers. Male sex; age older than 50 years; increased levels of alanine aminotransferase, aspartate aminotransferase, or gamma-glutamyl transferase; and low numbers of platelets were associated with higher liver fibrosis burden. We did not find evidence for a relationship between lung function and liver fibrosis. Controlled attenuation parameter >/=280 dB/m, suggesting severe steatosis, was detected in 39% of PiZZ carriers vs 31% of controls. Carriers of PiZZ had lower serum concentrations of triglyceride and low- and very-low-density lipoprotein cholesterol than controls, suggesting impaired hepatic secretion of lipid. Livers from PiZ-overexpressing mice had steatosis and down-regulation of genes involved in lipid secretion. CONCLUSIONS: In studies of AATD adults with the PiZZ mutation, and of PiZ-overexpressing mice, we found evidence of liver steatosis and impaired lipid secretion. We identified factors associated with significant liver fibrosis in patients, which could facilitate hepatologic assessment and counseling of individuals who carry the PiZZ mutation. ClinicalTrials.gov Number NCT02929940.
PubMed ID: 31121167
Publication type: Not specified
Citation: Gastroenterology. 2019 Sep;157(3):705-719.e18. doi: 10.1053/j.gastro.2019.05.013. Epub 2019 May 20.
Date Published: 24th May 2019
Registered Mode: Not specified
Created: 8th Jun 2020 at 06:35