These 21 SNPs were also genotyped for the replication study (916 patients with ACPA-negative RA and 3,764 healthy controls), and again the significant association of ORs between the two RA subsets was obtained (r = 0.45, P = 0.038, Figure 2A and detailed in Additional file 7). The gene discussed is PRTN3; the disease is rheumatoid arthritis.