APOLIPOPROTEIN-E POLYMORPHISM AND ALZHEIMERS-DISEASE

Apolipoprotein E (apoE) is associated with Alzheimer's neurofibrillary tangles and beta-amyloid protein in senile plaques. It also appears t o play an important part in the redistribution of lipids that follows deafferentation and neurodegeneration in the brain. The gene for apoE is on chromosome 19, within the genomic region previously associated w ith late-onset familial Alzheimer's disease (AD). We have studied apoE phenotype expression and the corresponding allele frequencies (epsilo n2, epsilon3, epsilon4) in 91 patients with sporadic AD and 74 control s. There was a significant association between epsilon4 and sporadic A D (epsilon4 frequency 0.380 in AD and 0.122 in controls, p <0.01). Ana lysis of epsilon4 allele frequency as a function of age revealed a bim odal distribution, with peaks at 65 and 75 years. In bearers of epsilo n4 in whom AD develops this tended to happen earlier in life than in t hose with epsilon3 or epsilon2. The epsilon4/AD association was more p ronounced in women. Octogenarians with AD had an epsilon4 allele frequ ency that was 3 times higher than one reported, in a different study, in healthy octogenarians. ApoE may be an important susceptibility fact or in the aetiopathology of sporadic AD.