PRTN3 and rheumatoid arthritis: In the Norwegian cohort, however, a significant interaction was detected, both in the total material and in the ACPA positive RA cases (AP = 0.4, 95%CI: 0.03–0.0.7 for RA in total and AP = 0.4, 95%CI: 0.05–0.7 for ACPA positive status in RA cases, Table 1).