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

<strong>Objectives:</strong> To explore the association of <i>TLR7</i> gene copy number variations (<i>CNVs</i>) with the susceptibility of ankylosing spondylitis (<i>AS</i>).<p></p> <p><strong>Methods:</strong> The case control study was performed in 649 Chinese Han patients with <i>AS</i> and 628 healthy controls. The copy numbers of <i>TLR7</i> gene (2 fragments) were measured by AccuCopy^TM methods. Chi-square and logistic regression models were performed to investigate the association of <i>TLR7</i> gene <i>CNVs</i> with <i>AS</i>. Odds ratio (ORs) and 95% confidence intervals (CIs) was calculated to estimate <i>AS</i> risk and the Bonferroni correction was applied owing to multiple testing.</p> <p><strong>Results:</strong> The logistic regression analysis showed that one copy was significantly associated with <i>AS</i> susceptibility after Bonferroni correction (for the <i>TLR7_1</i> fragment: OR=1.458, 95%CI(1.098,1.936), <i>p</i>=0.009; for the <i>TLR7_2</i> fragment: OR=1.451, 95%CI (1.093,1.927), <i>p</i>=0.010), and this association still exists after adjustment of age and sex (for the <i>TLR7_1</i> fragment: adjusted OR=2.066, 95%CI (1.318,3.238), <i>p</i>=0.002; for the <i>TLR7_2</i> fragment: adjusted OR=2.061, 95%CI (1.315,3.230), <i>p</i>=0.002). However, logistic regression analysis stratified by gender showed a higher OR in males (for the <i>TLR7_1</i> fragment: OR(95%CI)=7.987(3.756,16.983); for the <i>TLR7_2</i> fragment: OR(95%CI)=7.947(3.738,16.897)) than in females (for the <i>TLR7_</i>1 fragment: OR(95%CI)=0.204(0.080,0.524); for the <i>TLR7_2</i> fragment: OR(95%CI)=0.204(0.080,0.524)).</p> <p><strong>Conclusions:</strong> We conclude that the lower copy number (=1) of <i>TLR7</i> gene confers a risk factor for <i>AS</i> susceptibility in males but protective factor in females.</p>