Association of an asporin repeat polymorphism with ankylosing spondylitis in Han Chinese population: a case-control study.

Objective: To investigate the role of a functional polymorphism consisting of an aspartic acid (D) repeat located in the asporin gene (ASPN) gene in the susceptibility to and clinical outcome of ankylosing spondylitis (AS). Methods: A total of 374 Chinese patients with ankylosing spondylitis and 421 controls of the same ethnic origin matched for age and sex were included in the study. The asporin D repeat polymorphism was genotyped by polymerase chain reaction with a fluorescent primer. Results: Significant differences between AS patients and controls were detected in the distribution of the 7 alleles found in our population. D14 and D16 alleles were significantly over-represented in AS patients (D14, P=0.001, odds ratio (OR)=1.857, 95% confidence interval(CI) 1.27-2.715; and D16, P < 0.0001, OR=2.605, 95% CI 1.75-3.879). D16 over-representation was more common in early-onset patients than in late-onset patients, although the difference did not reach significance (P= 0.071). Conclusion: The results support a role for an asporin D repeat polymorphism in the susceptibility to AS and an influence of this gene on the outcome of the disease. D14 and D16 allele variants of ASPN might be the susceptibility alleles for AS in the Han Chinese population, whereas the D13 allele variant may have a protective effect on the onset of AS.