SLCO1B1 and rheumatoid arthritis: We developed clinical pharmacogenetic index for the prediction of DAS28 after 6 months of MTX monotherapy in Slovenian RA patients consisting of DAS28 at diagnosis, presence of erosions, MTX dose, SLC19A1 rs1051266, SLCO1B1 rs2306283, TYMS rs347430033, and AMPD1 rs17602729.