PRTN3 and rheumatoid arthritis: When available data on anti-citrullinated peptides antibodies were taken into account, however, sub-grouping of RA patients into ACPA-positive (n = 797) and ACPA-negative (n = 511) individuals provided evidence of an association regarding ACPA-negative RA for three markers, namely SNPs rs324389 [p = 0.008, OR = 0.802 (95% CI 0.681–0.944)], rs324981 [p = 0.026, OR = 0.837 (95% CI 0.716–0.979)] and rs324987 [p = 0.041, OR = 0.848 (95% CI 0.724–0.993)] (Table 1).