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Association of TLR4 (896A/G and 1196C/T) Gene Polymorphisms with Asthma Risk: A Meta-Analysis

Shaojun Li, Xinming Xie, Yang Song, Haoxiang Jiang, Xiaojuan Wu, Xiaofan Su, Lan Yang, Manxiang Li

Department of Respiratory Medicine, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China (mainland)

Med Sci Monit 2015; 21:3591-3599

DOI: 10.12659/MSM.895380

Available online:

Published: 2015-11-20

BACKGROUND: Conflicting data have been reported on the association between Toll-like receptor 4 (TLR4) +896A/G and +1196C/T polymorphisms and the risk of asthma. Therefore, we conducted this meta-analysis to clarify the effect of TLR4 +896A/G and +1196C/T polymorphisms on the risk of asthma.
MATERIAL AND METHODS: An electronic literature search was performed using PubMed, Embase, Web of Science, Chinese National Knowledge Infrastructure (CNKI), and Wanfang Data to find relevant studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of the associations. All statistical analyses were conducted using STATA software version 12.0.
RESULTS: A total of 14 studies with 2873 asthma cases and 3110 controls were included. The pooled results indicated a significant association between TLR4 +1196C/T polymorphism and the risk of asthma (T vs. C: OR=0.79, 95%CI=0.63–0.99, P=0.04; TT+CT vs. CC: OR=0.76, 95%CI=0.59–0.96, P=0.03; CT vs. CC: OR=0.74, 95%CI=0.58–0.95, P=0.02). In subgroup analysis by ethnicity, TLR4 +1196C/T polymorphism was significantly associated with asthma risk in Asians (T vs. C: OR=0.73, 95%CI=0.54–0.98, P=0.04; TT+CT vs. CC: OR=0.70, 95%CI=0.51–0.96, P=0.03; CT vs. CC: OR=0.69, 95%CI=0.50–0.96, P=0.03), but not in whites. For TLR4 +896A/G polymorphism, no significant association was found between TLR4 +896A/G polymorphism and asthma risk under any genetic models.
CONCLUSIONS: The results of this meta-analysis suggest that T allele of the TLR4 +1196C/T might act as a protective factor against the development of asthma.

Keywords: Asian Continental Ancestry Group - genetics, Alleles, Asthma - genetics, Case-Control Studies, European Continental Ancestry Group - genetics, Genetic Predisposition to Disease, Odds Ratio, Polymorphism, Single Nucleotide, Risk Factors, Toll-Like Receptor 4 - genetics