Background: Gout and IgA nephropathy (IgAN) are two prevalent extra-intestinal symptoms of inflammatory bowel disease (IBD). However, no randomized controlled experiment has found a link between Crohn's disease (CD) and gout or IBD and IgAN. Thus, the causal relationship between IBD, gout, and IgAN is studied using two-sample Mendelian Randomization and Genome-wide association studies (GWAS) summary statistics.
Methods: Several quality control processes were used to select qualified instrumental SNPs associated with exposure. To ensure the trustworthiness of the conclusion, inverse variance weighted, MR Egger, weighted median, and weighted mode methods were used. To estimate eligible instruments' stability, horizontal pleiotropy, and heterogeneity, leave-one-out analysis, MR-Egger intercept, and Cochran's Q test were used.
Results: At a genetic level, MR analysis revealed that gout was associated with CD (IVW: P = 0.01). IBD was also found to increase the probability of IgAN (IVW: P = 4.77e-7).
Conclusions: Gout increased the likelihood of CD, and IBD caused IgAN, according to a Mendelian randomization study. A larger sample size is required to discuss further the causal influence of gout on Crohn's disease.