Objective: To investigate the association between the polymorphism of tumor necrosis factor alpha 308 gene (TNF-alpha-308) promoter and the risk of chronic obstructive pulmonary disease (COPD) using the method of meta-analysis.
Method: The database of Medline and the Chinese biomedicine disc (CBM) were searched for published case-control studies of the association between the polymorphism of TNF-alpha-308 gene promoter and COPD. Data were extracted using a standardized form and the meta-analysis was performed.
Results: Eighteen case-control studies, comprising 1606 patients with COPD and 2551 controls (the oriental population: 666 patients with COPD and 898 controls; the Caucasian: 940 patients with COPD and 1653 controls) were included in the meta-analysis. Using a fixed effect model, the pooled result in the oriental population showed that the TNF2 allele was associated with the susceptibility to COPD [odds ratio (OR) = 2.62, 95% confidence interval (95% CI) 2.00 to 3.43]. The OR for COPD susceptibility in TNF1/2 population was significantly increased at 2.44 (95% CI 1.79 to 3.33) compared to the TNF1/1 population. The OR for COPD susceptibility in the TNF1/2 plus TNF2/2 population was significantly increased at 2.78 (95% CI 2.06 to 3.75) compared to the TNF1/1 population. When adjusted for smoking, the result was similar. However, in the Caucasian population, the TNF2 allele was not associated with the susceptibility to COPD (OR = 0.97, 95% CI 0.84 to 1.14). There was no association between the genotype of TNF-alpha-308 and COPD (OR = 0.96, 95% CI 0.79 to 1.16, and OR = 1.03, 95% CI 0.86 to 1.25), compared between the TNF1/2 population, the TNF1/2 plus the TNF2/2 population and the TNF1/1 population respectively. When adjusted for smoking, the result was similar.
Conclusion: In the oriental population, the TNF2 allele confers a significant risk for developing COPD. There is no association between the polymorphism of TNF-alpha-308 gene promoter and COPD in the Caucasian population.