Polymerase chain reaction analysis for the tumor necrosis factor alpha-308 (G>A) gene polymorphism in relation to ankylosing spondylitis

Objective To investigate the association between tumor necrosis factor α (TNF α) gene polymorphism and ankylosing spondylitis (AS).Methods Genomic DNA from 98 Chinese AS patients and 70 ethnically matched controls were typed for TNF(308) polymorphism by allele specific polymerase chain reaction (AS PCR).Results The TNF genotypes in AS patients were respectively TNF1 homozygote 37%,TNF2 homozygote 10% and TNF1 and TNF2 heterozygote 53%.While TNF genotypes in controls group were respectively TNF1 homozygote 67%,TNF2 homozygote 3% and TNF1 and TNF2 heterozygote 30%.Significant difference was found in the distribution of TNF 308 genotype between both groups ( χ 2=15 73, P 0 001).The frequencies of TNF alleles in AS patients were 63% for TNF1 and 37% for TNF2,while they were 82% for TNF1 and 18% for TNF2 in the control group.TNF2 allele frequency in AS patients was significantly increased compared with the control ( χ 2=9 053, P 0 05;OR=2 68,95% CI 1 394～5 135).Conclusion There is a strong association between the TNF α gene polymorphism and ankylosing spondylitis.TNF2 gene may play a role in AS susceptibility;allele specific polymerase chain reaction is a simple and specific method for the detection of TNF α 308 gene polymorphism.