Association Between PNPLA3 rs738409 C>G Variant and Liver-Related Outcomes in Patients With Nonalcoholic Fatty Liver Disease

Abstract

Patients with nonalcoholic fatty liver disease (NAFLD) have an increased risk for liver-related complications, such as decompensation, hepatocellular carcinoma (HCC), and death; the severity of liver fibrosis and metabolic comorbidities are the main risk factors. A single nucleotide polymorphism in patatin-like phospholipase domain-containing-3 (PNPLA3) gene is associated with higher prevalence of liver damage and HCC, but there are no data from prospective studies of outcomes of patients with this polymorphism. We investigated whether the common rs738409 variant in PNPLA3 gene associates with the occurrence of liver-related events and death in a large cohort of patients with NAFLD. We followed 471 consecutive individuals at a hospital in Italy with a diagnosis of NAFLD based on histologic factors or a diagnosis of compensated NAFLD-related cirrhosis based on clinical factors for at least 6 months, from March 2004 through December 2018. We collected data on the occurrence of hepatic and extrahepatic outcomes, including decompensation and HCC, cardiovascular events and extrahepatic cancers, and overall and liver-related death. We detected the rs738409 G>C polymorphism in DNA from patient blood samples using the TaqMan assay. During a median follow-up time of 64.6 months (range 6.1-175 months) 26 cases of decompensation, 13 HCCs, and 16 deaths (12 liver-related) were recorded. All liver-related events, including liver-related death, occurred in patients with F3 fibrosis or cirrhosis. The prevalence of PNPLA3 rs738409 GG, GT, and TT genotypes was 31.8%, 45.6%, and 22.6%, respectively. After adjusting for clinical, metabolic, and histologic risk factors, PNPLA3 C>G variant was associated with a higher risk of decompensation (hazard ratio [HR], 2.10; 95% CI, 1.03-4.29; P = .04), HCC (HR, 2.68; 95% CI, 1.01-7.26; P = .04), and liver-related death (HR, 3.64; 95% CI, 1.18-11.2; P=.02) by multivariate Cox regression analysis. In the subgroup of 162 patients with F3 fibrosis or cirrhosis, we confirmed the independent association between the PNPLA3 variant and decompensation (HR, 2.00; 95% CI, 1.01-3.97; P = .04), HCC (HR, 2.66; 95% CI, 1.02-7.13; P=.04), and liver-related death (HR, 3.64, 95% CI, 1.18-11.2; P = .02). We found no association between PNPLA3 genotype and cardiovascular events, extrahepatic cancers, or overall mortality. Patients with NAFLD carrying PNPLA3 rs738409 G>C variant are at higher risk of liver-related events and death.