The diagnostic value of VDR and CYP27B1 methylation levels for RA diagnosis was also assessed, and the AUCs of VDR and CYP27B1 were 0.628 (0.559–0.698) and 0.645 (0.575–0.714), respectively (Figure 2). The gene discussed is CYP27B1; the disease is rheumatoid arthritis.