ASSOCIATION OF COMPLEMENT ALLELES C4AQ0 AND C4B5 WITH RHEUMATOID-ARTHRITIS IN KOREANS

Objective-To investigate the association of complement C4 allotypes wi th rheumatoid arthritis in Koreans. Methods-65 rheumatoid arthritis pa tients and 255 controls were typed for C4 allotypes and HLA-A, B, C, D R, and DQ antigens. Results-The frequencies of C4AQ0 (32.3% v 14.9%, P < 0.005) and C4B5 (29.2% v 12.2%, P < 0.005) were significantly incre ased in rheumatoid arthritis patients compared with healthy control su bjects. Among rheumatoid patients, the frequency of C4AQ0 was signific antly increased in both the rheumatoid factor (RF) positive (27.3%) an d the RF negative (66.7%) subgroups. The frequencies of C4B5 and HLA-D R4 were significantly increased only in RF positive subgroup. C4B5 was strongly associated with HLA-DR4, whereas C4AQ0 did not show associat ion with DR4. Conclusions-In Koreans, C4AQ0 and C4B5 are associated wi th susceptibility to rheumatoid arthritis, as in the Japanese. C4B5 is strongly associated with HLA-DR4. C4AQ0 is considered to be a DR4 ind ependent risk factor, and a disease susceptibility allele in linkage d isequilibrium with C4AQ0 is suggested in Korean patients with rheumato id arthritis.