Identification of single nucleotide polymorphisms in the tumor necrosis factor (TNF) and TNF receptor superfamily in the Korean population

The tumor necrosis factor (TNF) and TNF receptor (TNF-TNFR) superfamily plays crucial roles in immune regulation and host immune responses. The superfamily has been also associated with many immune-mediated diseases such as asthma, rheumatoid arthritis, inflammatory bowel disease, and diabetes. In order to investigate genetic variants of the TNF-TNFR superfamily, a total of 63 known single nucleotide polymorphisms (SNPs) in the coding region (cSNPs) of the TNF-TNFR superfamily genes were selected from the public SNP database. Among 63 cSNPs tested in this study, only 24 SNPs (38%) were validated to be polymorphic in the Korean population by primer extension-based SNP genotyping. By means of the new enhanced single strand conformational polymorphism (SSCP) method, we also identified a total of 78 SNPs, including 48 known SNPs and 30 novel SNPs, in the 44 human TNF-TNFR super-family genes. The newly discovered SNPs in the TNF-TNFR superfamily genes revealed that the Korean population had very different patterns of allele frequency compared with African or white populations, whereas Korean allele frequencies were highly similar to those of Asian (correlation coefficient r = 0.88, p < 0.046). A higher similarity of allele frequency was observed between Korean and Japanese populations (r = 0.90, p < 0.001). The validated SNPs in the TNF-TNFR superfamily would be valuable for association studies with several immune-mediated human diseases.