Prevalence of apolipoprotein E alleles in healthy subjects and survivors of ischemic stroke: an Italian Case-Control Study.

BACKGROUND AND PURPOSE The epsilon4 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 from the same ethnic background. RESULTS The frequency of the apoE epsilon4 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 epsilon4 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, epsilon3/epsilon3 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 epsilon4 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.