Associations between chronic hepatitis B infection and inflammatory bowel diseases in East Asian populations

This study aims to investigate the effect of chronic hepatitis B (CHB) infection on inflammatory bowel disease (IBD) in East Asian populations. This study utilized summary statistics from genome-wide association studies (GWAS) on CHB infection, IBD, and its subtypes, including ulcerative colitis (UC) and Crohn’s disease (CD), in East Asian populations. A two-sample bidirectional Mendelian randomization (MR) analysis was conducted using various methods, including MR-Egger, weighted median, inverse-variance weighted (IVW), simple mode, and weighted mode. Sensitivity analyses were also performed to evaluate the robustness of the results. Forward MR analysis indicated that genetic susceptibility to CHB is a risk factor for total IBD (OR = 1.66, 95% CI = 1.48–1.87, <i>p</i> &lt; 0.001) and its subtype CD (OR = 2.25, 95% CI = 1.84–2.74, <i>p</i> &lt; 0.001) after Bonferroni correction. Genetic susceptibility to total IBD, UC or CD were not associated with CHB in the reverse MR analysis. Sensitivity analyses confirmed the robustness of the bidirectional MR results. This study suggests that genetic susceptibility to CHB infection is significantly associated with total IBD, particularly CD, in East Asian populations. This highlights the need for further investigation into the pathogenic mechanisms underlying this association.