Autoimmune thyroid diseases, celiac disease and gluten-free diet: a Mendelian randomisation study

Previous studies have reported co-morbidities of autoimmune thyroid disorders (AITD), including Hashimoto's disease and Graves' disease and celiac disease (CeD), as well as the possible beneficial effects of a gluten-free diet (GFD) on AITD. Nonetheless, it remains uncertain whether there is a genetic causal relationship between AITD and CeD, while the beneficial effects of a GFD are controversial. This study aims to explore the causal relationship between CeD and AITD, particularly with Hashimoto's disease, and to determine whether a GFD is beneficial for AITD. We performed a two-sample Mendelian randomisation analysis on data from the largest meta-analysis summary statistics of AITD, CeD and GFD. Genetic instrumental variables were established by pinpointing SNP that relate to corresponding factors. In assessing sensitivity and heterogeneity, we conducted examinations of MR Egger, weighted median, simple mode, weighted mode and MR Egger intercept tests. Hashimoto's disease was found to play a pathogenic role in increasing the risk of CeD (OR_IVW = 1·544 (95 % CI 1·153, 2·068), P = 0·00355), and our Mendelian randomisation study does not support genetic liability related to CeD with Graves' disease and GFD with AITD. This study supports the positive correlation between Hashimoto's disease risk and CeD risk, while GFD has no protective effect on AITD and may exert its effect through other mechanisms. These findings provide valuable insights into potential targets for disease intervention and treatment at the genetic level.