Effect of Interferon-γ Polymorphisms on Ankylosing Spondylitis: A Case-Control Study.

BACKGROUND This research aimed to explore the effects of interferon-γ (IFN-γ) polymorphisms and expression profile on susceptibility to ankylosing spondylitis (AS) in a Chinese population. MATERIAL AND METHODS Blood samples were collected from 89 AS patients and 106 healthy controls. IFN-γ polymorphisms were genotyped by polymerase chain reaction (PCR) and sequencing methods. The genotype distribution of polymorphism in the control group was detected by Hardy-Weinberg equilibrium (HWE). Odds ratios (OR) with 95% confidence intervals (95%CI) were calculated using the χ² test to evaluate the association between AS susceptibility and IFN-γ polymorphisms. Moreover, serum IFN-γ level was measured by ELISA. RESULTS rs1861493 and rs2430561 polymorphisms were conformed to be in HWE in genotypes distribution of the control group (P>0.05 for both). However, only TT genotype and T allele of rs2430561 presented significantly higher frequencies in AS patients than in healthy controls (P=0.04 and 0.03, respectively), indicating that they obviously increased the risk of AS in a Chinese population (OR=2.54, 95%CI=1.01-6.40; OR=1.60, 95%CI=1.04-2.46). In AS patients, serum IFN-γ level was higher than in controls, and its expression patterns showed significant association with genotypes of rs2430561. CONCLUSIONS IFN-γ rs2430561 polymorphism may contribute to the risk of AS through influencing IFN-γ expression.