HLA-DRB1 His13 was reported to have the strongest association with risk of ACPA-positive RA in a mixed East Asian population comprising South Korean and Han Chinese in Beijing [19], while an earlier study in a homogenous Korean population demonstrated HLA-DRB1 Val11 was strongly associated with risk for ACPA-positive RA [17]. This evidence concerns the gene PRTN3 and rheumatoid arthritis.