PRTN3 and rheumatoid arthritis: Interestingly, subjects ‘at risk’ for developing RA, which is defined by the positivity of rheumatoid factor (IgM-RF) or anti-citrullinated peptide autoantibodies (ACPA) along with arthralgia or a family history of RA, have a similar resting heart rate to RA patients, that is higher than healthy subjects.