Pregnane X Receptor Polymorphisms and Risk of Inflammatory Bowel Disease: A Meta-Analysis

Background: Pregnane X receptor (PXR) gene polymorphisms have been widely studied in terms of the association with inflammatory bowel disease (IBD), with inconsistent results. Objective: The present meta-analysis was performed to assess the association between PXR gene polymorphisms and the susceptibility of IBD, Crohn's disease (CD), and ulcerative colitis (UC). Methods: PubMed, Wanfang, and CNKI databases were searched for eligible studies before November 1, 2016. Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to calculate the various genetic models using either a fixed-effect or a random-effect model. The heterogeneity of the included studies was examined with Cochran Q and I-2 statistics. Begg's rank correlation test and Egger's linear regression test were used to assess the publication bias. Results: A total of six studies with 4248 cases and 3853 controls were included in this meta-analysis. Three PXR gene polymorphisms were evaluated: rs1523127, rs2276707, and rs6785049. Our analyses of rs1523127, rs2276707, and rs6785049 suggested that PXR gene polymorphism had no obvious influence on the risk of IBD in Caucasians. Subgroup analyses based on disease type showed similar results. Conclusion: Our meta-analysis revealed that PXR gene polymorphism may not be significantly associated with IBD susceptibility. However, the number of original studies was limited and further studies with large samples are needed to verify the results.