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% CI, 0.56-0.85). CONCLUSIONS These results demonstrate the importance of ethnicity in identifying specific COPD genes.