Association between CTLA-4 gene polymorphism and ankylosing spondylitis: a case-control study

Aims: The aim of our study was to evaluate the association between CTLA-4 polymorphisms (+49A/G, -318C/T and CT60A/G) and ankylosing spondylitis (AS) susceptibility. Methods: A total of 120 AS cases and healthy controls, matched on the age and gender, were enrolled in the study. Polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) were used to determine the gentypes of +49A/G, -318C/T and CT60A/G polymorphisms. Genotype distribution in control group was assessed by Hardy Weinberg Equilibrium (HWE) test. Odds ratio (OR) with 95% confidence interval (95% CI) were adopted to evaluate the relationship of CTLA-4 polymorphisms and AS susceptibility. Results: In our study, genotype distribution of the three polymorphisms in control group was consistent with the HWE (P > 0.05). The genotype analysis showed that AA genotype of + 49A/G polymorphism could increase the risk for AS (OR=2.357, 95% CI=1.127-4.930). Moreover, the frequency of A allele was also presented as a risk factor for AS. Additionally, AA genotype and A allele of CT60A/G appeared to be related with AS susceptibility (OR=2.610, 95% CI=1.047-6.510; OR=1.751, 95% CI=1.160-2.641). However, the T allele of -318C/T appeared to be a protective factor for AS (OR=0.383, 95% CI=0.228-0.643). Conclusion: In summary, there existed significant association between CTLA-4 gene polymorphisms and increased or decreased risk for AS.