Causal roles of gut microbiota in cholangiocarcinoma etiology suggested by genetic study

Figure 1 The process of present mendelian randomization analyses is shown in flow chart. A: Principle diagram of mendelian randomization study; B: Diagrammatic illustration of the complete mendelian randomization analysis process. Other risk factors influencing the occurrence of cholangiocarcinoma include exposure to fluke infections, inflammatory bowel disease, intrahepatic bile duct stones, choledochal cysts, and primary sclerosing cholangitis. Assumption 1: The instrumental variables (IVs) selected for this study should demonstrate a significant association with gut microbiota; Assumption 2: The IVs chosen for present study are required to have no significant associations with other potential confounding factors; Assumption 3: The IVs utilized in present study do not have any independent causal pathways leading to the outcome (CCA) other than through gut microbiota. MR: Mendelian randomization; IV: Instrumental variable; CCA: Cholangiocarcinoma; GC: Gallbladder cancer; eCCA: Extrahepatic cholangiocarcinoma; iCCA: Intrahepatic cholangiocarcinoma; LD: Linkage disequilibrium; SNPs: Single nucleotide polymorphisms.