Apolipoprotein E epsilon 4 allele in Alzheimer's disease and vascular dementia.

The frequency of the epsilon 4 allele of the apolipoprotein E (apoE) is increased in familial and sporadic late-onset Alzheimer's disease, but its prevalence in non-Alzheimer dementias in Caucasian populations is unknown. We found that the frequency of the apoE epsilon 4 allele was 0.45 in 93 Alzheimer's disease patients, 0.46 in 23 vascular dementia patients, 0.31 in 13 dementia of the frontal type patients, and 0.18 in 51 elderly controls. The association of apoE epsilon 4 allele is not unique to Alzheimer's disease, and its importance as a risk factor for the disease should be reconsidered.