TNFSF11 and rheumatoid arthritis: Our present study was conducted to evaluate the role of the RANK (rs8086340, C > G; rs1805034, C > T) and RANKL (rs7325635, G > A; rs7988338 G > A) SNPs as potential diagnostic biomarkers associated with the RA risk in the Polish population, and prognostic biomarkers affecting the outcome of the biological treatment.