PRTN3 and rheumatoid arthritis: The diagnosis of RA can be established in a patient with inflammatory arthritis involving three or more joints, positive rheumatoid factor (RF) and/or anti-citrullinated peptide/protein antibody (ACPA), disease duration of more than six weeks, and elevated C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR), but with no evidence of alternative diagnoses [22].