PRTN3 and rheumatoid arthritis: Current research indicates that patients positive for rheumatoid factor (RF) or anti-citrullinated peptide antibodies (ACPA) generally suffer from a more severe form of inflammatory arthritis, which is often erosive and poses an increased risk of evolving into rheumatoid arthritis (RA) (Kamali et al., 2005; Mohammed et al., 2009; Ryu et al., 2013; Molano-González et al., 2019).