Angiotensin-converting Enzyme I/D Polymorphism is Associated with COPD Risk in Asian Population: Evidence from a Meta-analysis

Several molecular epidemiological studies were conducted in recent years to evaluate the risk of chronic obstructive pulmonary disease (COPD) associated with insertion/deletion (I/D) polymorphism of angiotensin-converting enzyme (ACE). However, the results remain conflicting rather than conclusive. To derive a more precise estimation of association between ACE polymorphism and the risk of COPD, we performed a meta-analysis from all available relevant studies. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. There was a markedly positive association between the D allele or DD genotype and COPD risk in Asians (D vs. I: OR = 1.55, 95% CI = 1.407-2.44; DD vs. II: OR = 2.53, 95% CI = 1.65-3.89; DD vs. DI/II: OR = 2.09, 95% CI = 1.09-4.03), but this association was not observed in Europeans (D vs. I: OR = 0.93, 95% CI = 0.75-1.15; DD vs. II: OR = 0.86, 95% CI = 0.56-1.33; DD vs. DI/II: OR = 0.88, 95% CI = 0.63-1.23). Our meta-analysis provides strong evidence that D allele and DD homozygous might be significant genetic molecular markers for COPD susceptibility in Asians, but not for Europeans. Additional well-designed large studies were required for the validation of our results.