PNPO and rheumatoid arthritis: As shown in Figure 8, the box plot indicated that the expression pattern of these key genes resembled to that in the training set (blood sample): FUT7, KCNJ2, and TREML2 were significantly upregulated, accompanied by distinct downregulation of BIN1, ZFP36, and PNPO, suggesting the biological significance of these key genes across different samples and their potential to serve as biomarkers for RA.