PRTN3 and Arthritis: ACPA have been suggested to play a role in the pathogenesis of RA: the occurrence of these autoantibodies antedates the clinical onset by several years [7], they are associated with a more aggressive and destructive disease course (compared to the CCP-negative subset) [8], and it has been suggested that antibodies targeting citrullinated fibrinogen are involved in the development of arthritis in mice [9].