Prevalence of apolipoprotein E alleles in healthy subjects and survivors of ischemic stroke - An Italian case-control study

Background and Purpose-The epsilon 4 allele of the apolipoprotein E (apoE) has been related to the occurrence of myocardial infarction, but its association with ischemic stroke is controversial. We have evaluated the relation between apoE alleles and the occurrence of cerebrovascular ischemia. Methods-The apoE epsilon genotypes of 100 patients with a documented history of ischemic stroke without clinically apparent dementia (stroke+) and 108 subjects without such history (stroke-) were determined. The relative frequency of the apoE alleles and genotypes was estimated in 398 healthy subjects aged <40 years h-om the same ethnic background. Results-The frequency of the apoE epsilon 4 allele in stroke+ (0.18 [95% CI, 0.12 to 0.25]) was higher than in stroke-(0.07 [95% CI, 0.03 to 0.12]; P<.001) or in healthy subjects (0.09 [95% CI, 0.07 to 0.12]; P<.001). Carriers of the epsilon 4 allele differed between stroke+ (0.30 [95% CI, 0.19 to 0.42]) and stroke-(0.12 [95% CI, 0.5 to 0.22]; P=.004) or healthy subjects (0.16 [95% CI; 0.12 to 0.22]; P=.015). Accordingly, epsilon 3/epsilon 3 homozygotes were less frequent in stroke+ (0.59 [95% CI, 0.45 to 0.71]) than in stroke-(0.72 [95% CI, 0.59 to 0.82]; P=.063) or in healthy subjects (0.73 [95% CI, 0.67 to 0.78]; P=.01). In a multiple logistic regression analysis, age (P<.03), positive family history (P<.04) and apoE (P<.002) independently contributed to a stroke history, with epsilon 4 carriers exhibiting a higher estimated risk (odds ratio, 5.05). Conclusions-Our data show an association between apoE gene and a personal history of ischemic stroke and support the possibility that the apoE gene is a susceptibility locus for the risk of cerebrovascular ischemic disease.