The following is a summary of “Graves Disease and Inflammatory Bowel Disease: A Bidirectional Mendelian Randomization,” published in the May 2023 issue of Endocrinology & Metabolism by Xian, et al.

Graves disease (GD) and inflammatory bowel disease (IBD) are common autoimmune diseases that significantly impact a patient’s quality of life. Previous epidemiological studies have suggested a potential association between GD and IBD. However, the existence of a causal relationship between these two diseases remains unclear. For a study, researchers sought to investigate a potential causal relationship between GD and IBD using bidirectional 2-sample Mendelian randomization (MR).

Bidirectional 2-sample MR analysis was performed using genome-wide association study summary data obtained from Biobank and the International Inflammatory Bowel Disease Genetic Consortium. Various methods, including random-effect inverse variance weighted, weighted median, MR-Egger regression, and MR-PRESSO, were employed to ensure the robustness of the causal effect. Heterogeneity was assessed using Cochran’s Q value. The presence of horizontal pleiotropy was evaluated using MR-Egger regression and leave-one-out analysis.

The study’s results indicated that genetically predicted IBD might increase the risk of GD by 24% (odds ratio [OR] 1.24, 95% CI 1.01-1.52, P = .041). Specifically, Crohn’s disease (CD) increased the risk of GD, while ulcerative colitis (UC) appeared to have a protective effect against GD. On the other hand, genetically predicted GD was found to slightly increase the risk of CD, although there was no evidence indicating that GD increased the risk of UC or IBD. The findings from the outlier-corrected analysis were consistent with the raw causal estimates.

The study suggested a potential higher comorbidity rate between GD and CD, while UC may act as a protective factor against GD. The underlying mechanism and common pathways linking the diseases required further investigation.

Source: academic.oup.com/jcem/article/108/5/1075/6865283