Alzheimer's disease and apolipoprotein E genotype in western Australia: An autopsy-verified series

Objective: To determine the relationship between the apolipoprotein E epsilon 4 allele and autopsy-verified Alzheimer's disease (AD) in an Australian population. Design: Retrospective case-control study. Setting: Royal Perth Hospital, Perth, Western Australia (a tertiary referral hospital). Subjects: 50 subjects with ''definite'' AD (according to the histological and clinical criteria of the Consortium to Establish a Registry for Alzheimer's Disease [CERAD]) and 30 control subjects who had died from a non-neurological disease were randomly selected from the hospital's neuropathology register. Outcome measures: Histological grading of brain sections stained with the modified Bielschowsky stain according to the criteria of CERAD; number (burden) of neuritic plaques; apolipoprotein E genotype (APOE). Results: Frequency of the epsilon 4 allele was significantly higher in the AD group (37%) than in the control group (2%) (chi(2)=25.8; P<0.00001). In the AD group, 50% of subjects were heterozygous for the epsilon 4 allele and 12% were homozygous, while in the control group one subject was heterozygous for the allele and none were homozygous. No association was seen between the epsilon 4 allele and neuritic plaque burden in the hippocampus, entorhinal cortex, middle frontal gyrus or inferior parietal lobule in subjects with AD. Conclusions: Our findings confirm an association between the epsilon 4 allele and autopsy-verified AD. The epsilon 4 allele may be an important risk factor for susceptibility to AD in the general Australian population.