Studies on correlation between single-nucleotide polymorphisms of tumor necrosis factor gene and different stages of ankylosing spondylitis.

To examine if there is any correlation between ankylosing spondylitis (AS) and TNF-α gene promoter single-nucleotide polymorphisms (SNP) and their associated haplotypes. Using restriction fragment length polymorphism-polymerase chain reaction method, the polymorphism of TNF-α-238, -308, -850, -857, -863 locus, and TNF-β +252 were analyzed in patients with progressive AS, stable AS and control. (1) Neither the genotypes nor the allele frequencies of TNF-α (-308), (-238), (-863), and TNF-β +252 showed differences in each group. TNF-α (-850) CC genotype and C allele frequency distribution was significantly higher in healthy controls group than in the stable and progressive groups. TNF-α (-857) CT, CC genotype, and C, T allele frequency showed differences in all groups. (2) Polymorphism linkage equilibrium test revealed that association of six TNF-α, β gene SNPs with haplotype GACTCG in progressive group is significantly higher than in the stable group and healthy control group (P < 0.05). TNF-α (-857), (-850) gene polymorphism may increase the susceptibility to AS, but do not reflect the disease active state. The CC genotype and C allele may play a protective role in the pathogenesis of AS. TNF-α (-308) may be a weak indicator reflecting the active state of AS. Haplotype GACTCG may indicate both the susceptibility and the activity of AS.