Interestingly, elevated levels of CTSL-1 (AUC=0.907), SORT1 (AUC=0.899), SAA-4 (AUC = 0.898), TNFRSF10A (AUC=0.891), ST6GAL1 (AUC=0.855) and CCL18 (AUC=0.854) discriminate RA patients and HDs with high specificity and sensitivity, suggesting the potential role of these proteins to diagnose RA patients. This evidence concerns the gene SAA4 and rheumatoid arthritis.