FEN1 and rheumatoid arthritis: This study identified seven drug targets for RA:, CCR6, HLA-DPA1,HLA-DRB1, IFNGR2, C5, ATP2A1and FEN1 based on several MR methods (Wald ratio/IVW, MR-Egger, weighted median method, horizontal multiplicity test and Cochran's Q heterogeneity test), which were able to exclude confounding factors of measurement and for measurement, while co-localization provided further strong evidence.