The -491A/T polymorphism of the Apolipoprotein E gene is associated with the ApoEepsilon4 allele and Alzheimer's disease.

Several studies have attempted to confirm the association between the recently reported polymorphism located at position -491 in the transcriptional regulatory region of the Apolipoprotein E (ApoE) gene and Alzheimer's disease (AD). Results have been inconclusive, possibly due to the use of clinically diagnosed subjects and controls only. In this retrospective case-control study of 149 (96 AD and 53 controls) brain samples we show that homozygosity for the -491A variant is associated with an increased risk of development of AD. The genotype is also strongly associated with the presence of at least one epsilon4 allele (an established risk factor for AD) in women but not in men.