title: Association of complement alleles C4AQ0 and C4B5 with rheumatoid arthritis in Koreans.
abstract: OBJECTIVE
  To investigate the association of complement C4 allotypes with rheumatoid arthritis in Koreans.
  
  
  METHODS
  65 rheumatoid arthritis patients and 255 controls were typed for C4 allotypes and HLA-A, B, C, DR, 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 increased in rheumatoid arthritis patients compared with healthy control subjects. Among rheumatoid patients, the frequency of C4AQ0 was significantly increased in both the rheumatoid factor (RF) positive (27.3%) and the RF negative (66.7%) subgroups. The frequencies of C4B5 and HLA-DR4 were significantly increased only in RF positive subgroup. C4B5 was strongly associated with HLA-DR4, whereas C4AQ0 did not show association with DR4.
  
  
  CONCLUSIONS
  In Koreans, C4AQ0 and C4B5 are associated with susceptibility to rheumatoid arthritis, as in the Japanese. C4B5 is strongly associated with HLA-DR4. C4AQ0 is considered to be a DR4 independent risk factor, and a disease susceptibility allele in linkage disequilibrium with C4AQ0 is suggested in Korean patients with rheumatoid arthritis.
authors.affiliation: Department of Clinical Pathology, Seoul National University College of Medicine, Korea.
authors.forename: M H
authors.initials: MH
authors.lastname: Park
authors.forename: M D
authors.initials: MD
authors.lastname: Oh
authors.forename: Y W
authors.initials: YW
authors.lastname: Song
authors.forename: H J
authors.initials: HJ
authors.lastname: Pai
authors.forename: F
authors.initials: F
authors.lastname: Takeuchi
authors.forename: K
authors.initials: K
authors.lastname: Tokunaga
authors.forename: G H
authors.initials: GH
authors.lastname: Hong
authors.forename: K S
authors.initials: KS
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D000483:Alleles; D001172:Arthritis, Rheumatoid / Q000208:ethnology* / Q000276:immunology*; D003181:Complement C4 / Q000032:analysis*; D015934:Complement C4a / Q000032:analysis; D015935:Complement C4b / Q000032:analysis; D004198:Disease Susceptibility; D005260:Female; D015804:HLA-DR4 Antigen / Q000032:analysis; D006801:Humans; D007723:Korea / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012217:Rheumatoid Factor / Q000032:analysis
chemical_list: D003181:Complement C4; D015804:HLA-DR4 Antigen; D015934:Complement C4a; D015935:Complement C4b; D012217:Rheumatoid Factor