Although clinical studies have revealed a potential link between Helicobacter pylori ( H. pylori) infection and irritable bowel syndrome (IBS), the causal relationship between them remains unknown. The objective of this study was to investigate whether H. pylori infection is causally associated with IBS.
A two-sample Mendelian randomization (MR) analysis using the inverse variance weighted (IVW), weighted mode, weighted median and MR-Egger methods was performed. We used the publicly available summary statistics data sets of genome-wide association studies (GWAS) for H. pylori infection in individuals of European descent (case = 1,058, control = 3,625) as the exposure and a GWAS for non-cancer illness code self-reported: IBS (case = 10,939, control = 451,994) as the outcome.
We selected 10 single nucleotide polymorphisms at genome-wide significance from GWASs on H. pylori infection as the instrumental variables. The IVW, weighted mode, weighted median and MR-Egger methods all provided consistent evidence that suggests a lack of causal association between H. pylori and IBS. MR-Egger regression revealed that directional pleiotropy was unlikely to be biasing the result (intercept = −1e-04; P = 0.831). Cochran’s Q-test and the funnel plot indicated no evidence of heterogeneity and asymmetry, indicating no directional pleiotropy.