Association of TLR7 gene copy number variations with ankylosing spondylitis in a Chinese population: a case control study.

OBJECTIVES: To explore the association of TLR7 gene copy number variations (CNVs) with the susceptibility of ankylosing spondylitis (AS).

METHODS: The case control study was performed in 649 Chinese Han patients with AS and 628 healthy controls. The copy numbers of TLR7 gene (2 fragments) were measured by AccuCopyTM methods. Chi-square and logistic regression models were performed to investigate the association of TLR7 gene CNVs with AS. Odds ratio (ORs) and 95% confidence intervals (CIs) was calculated to estimate AS risk and the Bonferroni correction was applied owing to multiple testing.

RESULTS: The logistic regression analysis showed that one copy was significantly associated with AS susceptibility after Bonferroni correction (for the TLR7_1 fragment: OR=1.458, 95%CI(1.098,1.936), p=0.009; for the TLR7_2 fragment: OR=1.451, 95%CI (1.093,1.927), p=0.010), and this association still exists after adjustment of age and sex (for the TLR7_1 fragment: adjusted OR=2.066, 95%CI (1.318,3.238), p=0.002; for the TLR7_2 fragment: adjusted OR=2.061, 95%CI (1.315,3.230), p=0.002). However, logistic regression analysis stratified by gender showed a higher OR in males (for the TLR7_1 fragment: OR(95%CI)=7.987(3.756,16.983); for the TLR7_2 fragment: OR(95%CI)=7.947(3.738,16.897)) than in females (for the TLR7_1 fragment: OR(95%CI)=0.204(0.080,0.524); for the TLR7_2 fragment: OR(95%CI)=0.204(0.080,0.524)).

CONCLUSIONS: We conclude that the lower copy number (=1) of TLR7 gene confers a risk factor for AS susceptibility in males but protective factor in females.