Meta-analyses on Suspected Chronic Obstructive Pulmonary Disease Genes A Summary of 20 Years' Research

Rationale: Chronic obstructive pulmonary disease (COPD) is a complex disorder with high mortality worldwide. Studies on the role of candidate genes and their polymorphisms in COPD development have so far produced ambiguous results. Objectives: The aim of this study was to reveal the role of COPD candidate genes using data collected in previous research. Methods: We performed meta-analyses on 20 polymorphisms in 12 genes, after searching the PubMed and Embase databases for publications on COPD. These genes involve three main pathways associated with COPD development: the inflammatory, protease-antiprotease balance, and antioxidant pathways. Measurements and Main Results: We obtained significant results for three TGFB1 polymorphisms, although these were based only on a few studies. The IL1RN VNTR polymorphism increases the risk for COPD (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.09-2.65), whereas the TNFA -308 G/A polymorphism does so only in Asian populations (OR, 2.01; 95% CI, 1.21-3.31). The GSTP1 I105V polymorphism was protective for COPD in Asian populations only (OR, 0.69; 95% Cl, 0.56-0.85). Conclusions: These results demonstrate the importance of ethnicity in identifying specific COPD genes.