title: The I/D polymorphism of angiotensin-converting enzyme gene and asthma risk: a meta-analysis.
abstract: BACKGROUND
  The insertion/deletion (I/D) polymorphism of angiotensin-converting enzyme (ACE) gene has been implicated in susceptibility to asthma, but a large number of studies have reported inconclusive results. The aim of this study is to investigate the association between the I/D polymorphism of ACE gene and asthma risk by meta-analysis.
  
  
  METHODS
  We searched Medline (Ovid), Pubmed, CNKI, Wanfang, and Weipu database, covering all papers until March 12, 2010. Statistical analysis was performed by using the software revman 4.2 (The Cochrane Collaboration, http://www.cochrane.org) and stata 10.0 (StataCorp, College Station, TX, USA, http://www.stata.com).
  
  
  RESULTS
  A total of 1946 cases and 2152 controls in 18 case-control studies were included in this meta-analysis. The results indicated that the DD homozygote carriers had a 59% increased risk of asthma, when compared with the homozygotes II and heterozygote DI [odds ratio (OR)=1.59, 95% confidence interval (CI): 1.16-2.18]. In the subgroup analysis by ethnicity, significant elevated risks were associated with DD homozygote carriers in Asians (OR=2.02 and 95% CI: 1.29-3.16 for DD vs DI+II) but not in Caucasians (OR=1.14 and 95% CI: 0.76-1.72 for DD vs DI+II). In the subgroup analysis by age, significant elevated risks were associated with DD homozygote carriers in children (OR=2.44 and 95% CI: 1.36-4.38 for DD vs II+DI) but not in adults (OR=1.54 and 95% CI: 0.94-2.51 for DD vs II+DI).
  
  
  CONCLUSIONS
  This meta-analysis suggested that the I/D polymorphism of ACE gene would be a risk factor of asthma. To further evaluate gene-to-gene and gene-to-environment interactions between polymorphisms of ACE gene and asthma risk, more studies with large groups of patients are required.
authors.affiliation: Department of Respiratory Medicine, West China Hospital of Sichuan University, Guoxuexiang 37, Chengdu, Sichuan, China.
authors.forename: Y-G
authors.initials: YG
authors.lastname: Zhang
authors.forename: X-B
authors.initials: XB
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: J
authors.initials: J
authors.lastname: Huang
authors.forename: C
authors.initials: C
authors.lastname: He
authors.forename: C
authors.initials: C
authors.lastname: Tian
authors.forename: Y
authors.initials: Y
authors.lastname: Deng
authors.forename: H
authors.initials: H
authors.lastname: Wan
authors.forename: D
authors.initials: D
authors.lastname: Shrestha
authors.forename: Y-Y
authors.initials: YY
authors.lastname: Yang
authors.forename: H
authors.initials: H
authors.lastname: Fan
mesh_terms: D001249:Asthma / Q000209:etiology / Q000235:genetics*; D005006:Ethnicity; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D016254:Mutagenesis, Insertional / Q000706:statistics & numerical data; D016017:Odds Ratio; D007703:Peptidyl-Dipeptidase A / Q000235:genetics*; D011110:Polymorphism, Genetic; D012307:Risk Factors; D017384:Sequence Deletion
chemical_list: D007703:Peptidyl-Dipeptidase A