The MR estimates of the whole 6 significant exposures in training and validation datasets were presented in Fig. 4C, D. In detail, DDIT4 exhibited the association with GCA risk with an OR of 5.1065 (95% CI 1.5281–17.0645) via Wald Ratio method, while ARHGAP15 was associated with the risk of GCA with an OR of 1.2622 (95% CI 1.0159–1.5683) calculated via IVW and 1.1917 (95% CI 0.8675–1.6372) calculated via MR-Egger in training dataset, and the results were further validated in validation dataset. This evidence concerns the gene DDIT4 and temporal arteritis.