No association between ApoE and schizophrenia: Evidence of systematic review and updated meta-analysis

Introduction: Schizophrenia affects between 0.3% and 2% of the worldwide population. A genetic contribution has been postulated in the development of this disorder. Genes such as ApoE have been implicated in the neurodevelopment associated with schizophrenia in case-control and meta-analysis studies, but the results remain inconclusive. Due to this, the aim of the present study was to explore the association between ApoE and schizophrenia through a meta-analysis. Material and methods: We collected all relevant studies by searching PubMed and EBSCO databases. The pooled odds ratios with 95% confidence intervals were calculated to estimate the association. The following models were evaluated: A) epsilon 4 vs epsilon 3, B) epsilon 4 vs epsilon 2, C) epsilon 4 vs epsilon 3+ epsilon 2, D) Caucasian population and E) Asian population. Statistical analyses were performed using EPIDAT 3.1 software. Results: The meta-analyses comprised 28 association studies, which included 4703 controls and 3452 subjects with schizophrenia. A significant protective effect was found for allele e3 in the Asian population (OR = 0.73, 95% CI = 0.54-0.98). No significant associations were observed in the other models and populations analyzed. Conclusions: Ourmeta-analysis suggests a protective association between ApoE allele epsilon 3 and schizophrenia in the Asian population. (C) 2015 The Authors. Published by Elsevier B.V.