PURPOSE: The -1237T/C polymorphism of the Toll-like receptor 9 (TLR9) gene has been implicated in the susceptibility of inflammatory bowel diseases (IBDs), but the results remain conflicting. We further investigated this association via meta-analysis. MATERIALS AND METHODS: Multiple electronic databases were extensively searched until February, 2015. The strength of association was evaluated by calculating the pooled odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: A total of 2987 cases and 2388 controls from eight studies were analyzed. Overall, association was found between TLR9 -1237T/C polymorphism and the risk of IBDs when all the studies were pooled (recessive model, OR: 1.59, 95% CI: 1.02-2.47, p=0.04; homozygote comparison, OR: 1.62, 95% CI: 1.04-2.52, p=0.03; allele model, OR: 1.13, 95% CI: 1.00-1.27, p=0.05). Stratification by ethnicity indicated an association between TLR9 -1237T/C polymorphism and IBDs risk in Caucasians (recessive model, OR: 1.59, 95% CI: 1.02-2.47, p=0.04; homozygote comparison, OR: 1.62, 95% CI: 1.04-2.52, p=0.03; allele model, OR: 1.12, 95% CI: 1.00-1.27, p=0.05). When stratified by disease type, significant correlation were only found in the Crohn's disease subgroup (recessive model, OR: 1.69, 95% CI: 1.05-2.73, p=0.03; homozygote model, OR: 1.74, 95% CI: 1.07-2.82, p=0.02; allele model, OR: 1.15, 95% CI: 1.01-1.32, p=0.04). CONCLUSION: The present study suggested that the TLR9 -1237T/C polymorphism might act as a risk factor in the development of IBDs, particularly in Caucasians.
Alleles ; European Continental Ancestry Group/genetics ; Genetic Predisposition to Disease/*genetics ; Homozygote ; Humans ; Inflammatory Bowel Diseases/ethnology/*genetics ; Odds Ratio ; Polymorphism, Genetic/*genetics ; Risk Factors ; Toll-Like Receptor 9/*genetics/metabolism