Objective: Ankylosing spondylitis (AS) is a chronic inflammatory disease affecting the sacroiliac joint and vertebral column. Tumor necrosis factor alpha (TNF-alpha), a cytokine that acts via two tumor necrosis factor receptors (TNFR1 and TNFR2), may be implicated in the pathogenesis of AS. The aim of the present study was to examine the role of the polymorphisms 36A>G (TNFR1), 676T>G (TNFR2), -857C>T (TNF-alpha), -308G>A (TNF-alpha), and -238G>A (TNF-alpha) in AS susceptibility.
Methods: Forty-nine AS patients and 68 randomly chosen healthy volunteers were enrolled in the study. Polymerase chain reaction coupled with a restriction fragment length polymorphism assay was performed in the genotype analysis of each variant.
Results: The polymorphisms 36A>G (TNFR1) and -238G>A (TNF-alpha were not found to be in Hardy-Weinberg equilibrium in the patient group and therefore were excluded from the statistical analysis. A marginally statistically significant difference was observed in the distribution of 676T>G (TNFR2) genotypes between AS patients and controls (p=0.054) and was revealed to be more significant in the 676T>G allele distribution between the two groups (p=0.031). The complex genotype TNFR2 676TG/ TNF-alpha -857CC (p=0.041) was also differently distri-buted between AS patients and controls.
Conclusions: The TNFR2 676T allele is reported here for first time to be differently distributed between AS patients and controls. The higher frequency of the wild type TNFR2 676T allele in AS patients suggests the functional ability of TNFR2 to support increased TNF-alpha mediated immunoactivity.