Gastroesophageal reflux disease (GERD) positively influences rheumatoid arthritis (RA), but RA has no significant influence on GERD, according to a study published in Frontiers in Genetics. Researchers examined the bidirectional causal effects between GERD and RA by two-sample Mendelian randomization (MR) analyses using genetic evidence for 129,080 GERD cases versus 602,604 controls and 6,236 RA cases versus 147,221 controls. The primary analysis used an inverse-variance weighted method. The researchers found valid evidence provided by both univariate (UV)MR and multivariate (MV)MR analyses that RA was causally and positively influenced by GERD (ORs; 1.49 and 1.69 for UVMR and MVMR, respectively), but RA did not influence GERD. “The results suggested that GERD can induce the occurrence of RA, whereas RA has no significant impact on GERD,” the authors wrote. “In particular, individuals with GERD are at a 69% higher risk of developing RA, highlighting GERD as a significant risk factor for this condition.”