PRTN3 and rheumatoid arthritis: Given the destructive nature of RA, early diagnosis and initiation of treatment is highly important.49, 50, 51 The recently revised diagnostic criteria for RA (European League Against Rheumatism) 201052 improved early diagnosis by including ACPA in the criteria but demonstrated even more early disease heterogeneity (only 50% of patients are positive), stressing the need for other diagnostic biomarkers for ACPA-negative disease.53