PRTN3 and Arthritis: In patients with an already high risk, for instance those who are ACPA-positive (for example, 42% developed arthritis in the Leeds cohort [19], 46% in the present study) or those with a high probability based on clinical prediction rules, having US abnormalities was almost always associated with arthritis development (6 patients in the present study, with a 100% chance of developing arthritis) [9, 17, 19].