title: Association between Apolipoprotein ε4 Gene Polymorphism and Risk of Ischemic Stroke: A Meta-Analysis.
abstract: BACKGROUND
  Previous studies examining the association of apolipoprotein E (APOE) gene polymorphism with the risk of ischemic stroke (IS) have yielded conflicting results. Therefore, we performed a meta-analysis to investigate the association between APOE ε4 gene polymorphism and risk of IS.
  
  
  CONCLUSIONS
  A literature search for genetic association studies published before May 30, 2015, was conducted in the PubMed, EMBASE and Google Scholar databases. The following search terms were used: (apolipoprotein E) or (APOE) and (ε4) and (polymorphism) or (polymorphisms) and ('ischemic stroke' or 'IS') and ('cerebral infarction' or 'CI') and ('genetic polymorphism' or 'single nucleotide polymorphisms' or 'SNP'). ORs and 95% CIs were used to calculate the strength of association. Begg's funnel plot was used to assess the potential for publication bias. In our meta-analysis, 26 case-control studies involving 6,397 IS cases and 19,053 controls were included. Overall significant association between carrier of ε4 allele and risk of IS was observed (OR 1.43, 95% CI 1.10-1.85, p = 0.007). In the subgroup analysis based on ethnicity, a significant association between Apo ε4 carrier and risk of IS was observed in Asian studies (OR 1.53, 95% CI 1.04-2.25, p = 0.031) whereas borderline significant association between APO ε4 carrier and risk of IS was observed in Caucasian studies (OR 1.36, 95% CI 0.95-1.93, p = 0.093).
  
  
  CONCLUSIONS
  Our meta-analysis suggests that APOE ε4 allele is associated with higher risk of IS in Asian population as compared to Caucasian population.
authors.affiliation: Department of Neurology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Department of Neurology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Kumar
authors.affiliation: Department of Neurology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Manya
authors.initials: M
authors.lastname: Prasad
authors.affiliation: Department of Neurology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Shubham
authors.initials: S
authors.lastname: Misra
authors.affiliation: Department of Neurology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Awadh
authors.initials: A
authors.lastname: Kishor Pandit
authors.affiliation: Department of Neurology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Kamalesh
authors.initials: K
authors.lastname: Chakravarty
keywords: Apolipoprotein-E; Association study; Cerebral infarction; Gene polymorphism; Ischemic stroke; Meta-analysis