Pregnane X receptor gene variant rs7643645 and total mortality in subjects with nonalcoholic fatty liver disease

Pregnane X receptor (PXR) gene variants rs7643645 and rs2461823 are reported to associate with clinically and histologically more severe liver injury in nonalcoholic fatty liver disease (NAFLD). It is known that the more progressive the NAFLD, the higher the hepatic and extra-hepatic mortality and morbidity. Thus, we investigated the total mortality in Finnish middle-aged ultrasonographically verified NAFLD patients with PXR rs7643645 AA/AG ( n = 217) or GG ( n = 27) variants and rs2461823 CC/CT ( n = 215) or TT ( n = 27) variants. In up to 30 years of follow-up, PXR rs7643645 GG subjects were at an increased risk of total mortality compared with AA/AG subjects, 1.676 (1.014-2.772), P = 0.044. The statistically significant difference prevailed after multiple adjustments for potentially confounding factors, RR, 2.024 (1.191-3.440), P = 0.009. In the subjects without NAFLD ( n = 731), the mortality risk was not associated with rs7643645 variants, 1.051 (0.708-1.560; P = 0.804). There was no difference in the total mortality between the PXR rs2461823 variant subgroups, 1.141 (0.663-1.962; P = 0.634). As the rs7643645 G variant disrupts a putative hepatocyte nuclear factor 4α binding site located in the PXR gene promoter and is associated with lower hepatic expression of PXR and its target genes, our result suggests that genetic disruption of xenobiotic metabolism increases mortality in subjects with NAFLD. Further studies are needed to confirm the results of the present study.