PRTN3 and rheumatoid arthritis: In an Italian study where 11 different commercial ACPA assays were compared investigating 100 RA patients and 202 healthy and disease controls, the AUC were largest for assays using CCP2 or anti-CCP3 as antigens, but lower when other citrullinated antigens (filaggrin, vimentin, IgG, Epstein Barr virus) were used.