Background: Several genetic studies have evaluated the association between Toll-like receptor 4 (TLR4) A299G polymorphism and the risk of pneumonia. However, the results were not consistent. We thus did this meta-analysis.
Material and Methods: Relevant studies were systematically searched by using the NCBI, Medline, Web of Science, and Embase databases. Data were extracted independently by 2 investigators. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated.
Results: Eight case-control studies with 658 patients and 1862 controls were included in this meta-analysis. TLR4 A299G polymorphism was significantly associated with pneumonia risk (OR=1.74; 95% CI 1.19–2.53; P=0.004). The result was significant in adults. In addition, TLR4 A299G polymorphism was also associated with community-acquired pneumonia (CAP) risk. Results from cumulative meta-analysis and sensitivity analysis suggested that the results are reliable and robust.
Conclusions: The results of this meta-analysis suggest that susceptibility to pneumonia was associated with TLR4 A299G polymorphism.

Keywords: Genetic Association Studies, Child, Preschool, Adult, Genetic Predisposition to Disease, Humans, Polymorphism, Single Nucleotide - genetics, Risk Factors, Toll-Like Receptor 4 - genetics