Notably, the prediction capacity of these biomarkers for RF- and/or ACPA-negative RA patients were verified in a much bigger subset of the validation cohort (n = 97 for RF-negative patients, n = 55 for ACPA-negative patients, and n = 45 for RF&ACPA-negative patients), with an overall prediction accuracy of 81%, 80% and 80%, respectively. This evidence concerns the gene PRTN3 and rheumatoid arthritis.