PRTN3 and rheumatoid arthritis: On the other hand, we found that seronegative subjects carrying the KLRCrs7301582T or KLRK1rs1049174C alleles showed a significantly increased risk of developing RA whereas no effect was detected in ACPA-positive individuals (ORDom-ACPA− = 1.56, 95%CI 1.18–2.09, P = 0.003 vs. ORDom-ACPA+ = 1.05, 95%CI 0.84–1.30, P = 0.67 and ORDom-ACPA− = 1.38, 95%CI 1.03–1.84, P = 0.031 vs. ORDom-ACPA+ = 1.09, 95%CI 0.88–1.35, P = 0.42).