Association between Angiotensin-Converting Enzyme I/D Polymorphism and Asthma Risk: A Meta-Analysis Involving 11,897 Subjects

Abstract

Background. Genetic susceptibility to asthma has been a research focus in the scientific community. Several studies have been conducted in recent years to evaluate the risk of asthma and insertion/deletion (I/D) polymorphism of angiotensin-converting enzyme (ACE). However, the results remain conflicting rather than conclusive. Methods. We carried out a search in Medline, EMBASE, and Chinese National Knowledge Infrastructure (CNKI) database for relevant studies. Data were extracted using a standardized form and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the strength of the association. Results. Our meta-analysis on 11,897 subjects from all available studies showed that the DD genotype was associated with increased asthma risk than those with the II (OR = 1.59, 95% CI = 1.20–2.12) or ID/II (OR = 1.62, 95% CI = 1.24–2.10) genotype. Stratified analyses by ethnicity (Europeans and Asians) and age (adults and children) obtained statistically similar results in the two genetic models. In the subgroup analysis by source of controls, the DD genotype was associated with a significantly elevated risk of asthma among population-based controls (DD vs. II: OR = 2.27, 95% CI = 1.45–3.56) but not hospital-based controls (DD vs. II: OR = 1.18, 95% CI = 0.93–1.49). Conclusions. This meta-analysis provides strong evidence that the I/D polymorphism of ACE is associated with asthma risk. Additional well-designed large studies were required for the validation of our results, especially in African populations.

• angiotensin-converting enzyme
• asthma
• meta-analysis
• polymorphism

Acknowledgments

The authors are extremely thankful to Julie Lee and Morten Dahl of Department of Clinical Biochemistry, Herlev University Hospital, Denmark, for providing original data of their study. They also thank Prof. Andrew G. Hawthorn of Department of Business Studies and International Trade, Ningbo University of Technology, Ningbo, for his review and scientific editing of the manuscript.

Declaration of Interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Author Contributions

Qun-Li Ding and Shi-Fang Sun contributed equally to this study.