The three other target-action pairs with inverse associations suggested across all four case groups and with a mean OR ≤0.80 were represented by one medication each: xanthine dehydrogenase/oxidase blockers (the anti-gout medication allopurinol, mean OR = 0.77), bifunctional purine biosynthesis protein PURH blockers (methotrexate, typically used to treat psoriasis, rheumatoid arthritis, and cancer, mean OR = 0.79), and targets of vascular endothelial growth factor A (the beta blocker carvedilol, used for hypertension and heart failure, mean OR = 0.80) (Table 2). This evidence concerns the gene XDH and rheumatoid arthritis.