SummaryTumor necrosis factor alpha (TNFA) is a cytokine, which is secreted from activated macrophage, with a broad range of biological activities. The gene encoding TNFA is located in tandem with the TNFB gene within the HLA complex on chromosome 6p21.3. We detected a single base polymorphism in the human TNFA gene promoter region in 300 unrelated Korean individuals. The TNFA promoter region which showed a G to A transition at position of -308 was investigated by NcoI restriction fragment length polymorphism analysis. A biallelic polymorphism of TNFA gene showed fragments of 87/20 bp and 107 bp acting as TNFA* 1 allele and TNFA*2 allele, respectively. The allele frequencies of TNFA* 1 and TNFA* 2 were 0.8783 and 0.1217, respectively. The 21.7% of heterozygosity was observed. No association between promoter region phenotypes of TNFA and the first intron phenotypes of TNFB was observed in Korean. Allele frequencies of Koreans were compared with that of Europeans.
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 14.90/., 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 C4AQO 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 C4AQO did not show association with DR4. Conclusions-In Koreans, C4AQO and C4B5 are associated with susceptibility to rheumatoid arthritis, as in the Japanese. C4B5 is strongly associated with HLA-DR4. C4AQO is considered to be a DR4 independent risk factor, and a disease susceptibility allele in linkage disequilibrium with C4AQO is suggested in Korean patients with rheumatoid arthritis. (Ann Rheum Dis 1996;55:776-778)
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