The insertion/deletion polymorphism in the angiotensin-converting enzyme and susceptibility to schizophrenia or Parkinson's disease: A meta-analysis

Introduction: The purpose of this study was to examine whether the insertion (I) and deletion (D) polymorphism of the angiotensin-converting enzyme (ACE) confers susceptibility to schizophrenia and Parkinsons disease (PD). Materials and methods: A meta-analysis was performed of the associations between the ACE I/D polymorphism and schizophrenia and PD. Results: Thirteen studies with 2024 cases and 2230 controls comprising eight studies on schizophrenia and five on PD were included in the meta-analysis. The meta-analysis revealed no association between the ACE D allele and schizophrenia (OR = 0.990, 95% CI = 0.8891.102, p = 0.856) or PD (OR = 1.067, 95% CI = 0.9071.255, p = 0.433). Stratification by ethnicity indicated no association between the ACE D allele and schizophrenia in European, Asian, or Turkish ethnic groups (OR = 0.896, 95% CI = 0.5661.419, p = 0.640; OR = 1.057, 95% CI = 0.9031.238, p = 0.492; OR = 1.111, 95% CI = 0.8891.389, p = 0.354, respectively). Ethnicity-specific meta-analysis was not conducted for PD because only one ethnic PD study was available. Conclusions: This meta-analysis found no association between the ACE I/D polymorphism and schizophrenia or PD.