CYP2R1 and rheumatoid arthritis: We also analyzed the influences of the main drug treatment on the methylation levels of these genes, and there were no significant associations regarding CYP24A1, CYP27B1, CYP2R1, and VDR methylation levels between RA patients being treated with glucocorticoid and without, as well as the patients being treated with methotrexate and without (Table 6).