GPR183 and rheumatoid arthritis: In our cohort, we found the mRNA levels of FAS, GPR183, and TFRC were increased in RA synovium compared to OA synovium (Figure 5(k)), and the AUCs of these genes for RA diagnosis in our cohort were 0.8144, 0.7904, and 0.7776, respectively (Figure 5(l)), consistent with the aforementioned findings in RNA sequencing results of synovial tissues.