When haplotype frequencies were compared between ACPA(+)RA patients and controls, three haplotypes including DRB1*04:05 were associated with the susceptibility of ACPA(+)RA (DRB1*04:05-DPB1*02:01; Permutation P<0.0001, DRB1*04:05-DPB1*04:02,; Permutation P = 0.0004, DRB1*04:05-DPB1*05:01; Permutation P<0.0001, S3 Table), suggesting the primary role of DRB1*04:05. Here, PRTN3 is linked to rheumatoid arthritis.