Genome-wide Analysis Identifies Novel Gallstone-susceptibility Loci Including Genes Regulating Gastrointestinal Motility

Abstract

Objective: Genome-wide association studies (GWAS) have identified several risk loci for gallstone disease. As with most polygenic traits, it is likely many genetic determinants are undiscovered. The aim of this study was to identify novel genetic variants that represent new targets for gallstone research and treatment. Design: We performed a GWAS of 28,627 gallstone cases and 348,373 controls in the UK Biobank and a GWA meta-analysis (43,639 cases and 506,798 controls) with the FinnGen cohort. We assessed pathway enrichment using gene-based then gene-set analysis and tissue expression of implicated genes in Genotype-Tissue Expression project data. We constructed a polygenic risk score (PRS) and evaluated phenotypic traits associated with the score. Results: Seventy-five risk loci were identified (P<5*10-8) of which forty-six were novel. Pathway enrichment revealed associations with lipid homeostasis, glucuronidation, phospholipid metabolism and gastrointestinal motility. ANO1 and TMEM147, both in novel loci, are strongly expressed in the gallbladder and gastrointestinal tract. Both regulate gastrointestinal motility. The gallstone risk allele rs7599-A leads to suppression of hepatic TMEM147 expression suggesting the protein protects against gallstone formation. Individuals in the highest decile of the PRS demonstrated a 6-fold increased risk of gallstones compared to the lowest risk category. The PRS was strongly associated with increased body mass index, serum liver enzyme and C-reactive protein concentrations and decreased lipoprotein cholesterol concentrations. Conclusion: This GWAS demonstrates the polygenic nature of gallstone risk and identifies 46 novel susceptibility loci. For the first time, we implicate genes influencing gastrointestinal motility in the pathogenesis of gallstones.