The analysis results showed that the AUC of peripheral blood circulating RF_IgA level in predicting RA was 0.79 (95% CI: 0.74-0.83, P < 0.001) (Figure 1(a)); the cut-off value was 28.91 IU/mL, and the sensitivity was 85.91%; the specificity was 63.86%. The gene discussed is CD79A; the disease is rheumatoid arthritis.