Notable exceptions are histones which are citrullinated in vivo, especially during apoptosis and NETosis, and hnRNP‐A2/B1.38 Importantly, autoantibodies and autoreactive T cells recognizing hnRNP‐A2/B1 and related proteins have been found in PIA and human RA.39, 40, 41, 42 Given that most ACPA‐positive RA patients are reactive with citrullinated histone peptides and/or hnRNP‐A2/B1, autoimmunity to citrullinated isoforms of nucleic acid binding proteins appears to be a common phenomenon in RA. This evidence concerns the gene PRTN3 and rheumatoid arthritis.