PRTN3 and rheumatoid arthritis: In 2010, the American College of Rheumatology/European League Against Rheumatism reported classification criteria for RA based on the extent of tenderness and swelling of the joints, serum levels of autoantibodies such as rheumatoid factor (RF) and anticitrullinated protein autoantibody (ACPA), levels of acute-phase reactants such as C reactive protein (CRP), erythrocyte sedimentation rate (ESR), and duration of symptoms.