Yao Ma, Xiang Tong, Ying Liu, Sitong Liu, Hai Xiong, Hong Fan

Angiotensin-converting enzyme (ACE) gene I/D polymorphism has been studied in relation to the susceptibility to COPD and COPD with pulmonary hypertension (PH) with inconclusive results. We performed the first comprehensive meta-analysis to evaluate accurately the association between the ACE gene polymorphism and the risk of COPD. Data were analyzed using odds ratios (ORs) and the corresponding 95% CIs to measure the strength of the models. Subgroup analyses were conducted by ethnicity and complication which referred to PH. In total, 15 studies (2,635 participants) were included in our study, of which four studies (288 participants) were for PH subgroup. The overall analysis results indicated that the ACE gene polymorphism was not associated with COPD susceptibility in all gene models. However, the ethnic subgroup analysis results indicated that ACE gene polymorphism was associated with Asians' susceptibility to COPD (DD+DI vs II, OR=1.47, P=0.019, 95% CI: 1.07-2.02). Further, the overall results of the present study detected no statistical significance between ACE gene polymorphism and the risk of COPD with PH, but the homozygote variant (DD) increased the risk of PH in Asian COPD patients (DD vs ID+II, OR=2.05, P=0.05, 95% CI: 1.00-4.19). The current study suggests that ACE polymorphism, particularly the homozygote variant (DD), might contribute to the risk of COPD and COPD with PH among Asians. Further studies with larger sample size and more ethnicities are expected to be conducted in the future to validate the results.