Attenuated effect of PNPLA3 on hepatic fibrosis by HSD17B13 in Japanese patients with non-alcoholic fatty liver disease

Background & Aims PNPLA3 rs738409 has been associated with increased risks of fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). Recently, carriage of the rs6834314 G allele, which is in high linkage with rs72613567 of 17-beta-hydroxysteroid dehydrogenase 13 (HSD17B13), was reported to be associated with a reduced risk of liver injury in NAFLD patients. We estimated the impact of these genetic variants on hepatic fibrosis in Japanese patients with NAFLD. Methods We analysed the associations of these genetic variants with liver histology in 290 Japanese patients with biopsy-proven NAFLD diagnosed during 2002-2019. During follow-up, 14 patients (4.8%) developed hepatocellular carcinoma. Results Prevalences of the PNPLA3 rs738409 genotypes were 0.17 for CC, 0.41 for CG, 0.42 for GG, and those for HSD17B13 rs6834314 were 0.54 for AA, 0.39 for AG and 0.07 for GG. There was no significant interaction between the PNPLA3 and HSD17B13 genotypes. Prevalences of advanced fibrosis according to PNPLA3/HSD17B13 genotypes were 0.16 for CC,CG/AG,GG, 0.20 for CC,CG/AA, 0.30 for GG/AG,GG and 0.37 for GG/AA. Multivariate analysis identified PNPLA3 GG as a predictor of advanced fibrosis (stage 3/4) in carriers of HSD17B13 AA (odds ratio 2.4, P = .041), but not HSD17B13 AG/GG (P = .776). The HSD17B13 genotype G was significantly associated with lower prevalences of severe inflammation and ballooning and tended to be associated with a higher prevalence of advanced steatosis. Conclusions In Japanese patients with NAFLD, carriage of the HSD17B13 rs6834314 G allele attenuated the effect of the PNPLA3 rs738409 GG genotype on advanced hepatic fibrosis.