Apolipoprotein E genotype in senile dementia and Down's syndrome

Apolipoprotein E genotypes were determined in 30 healthy elderly controls, 42 patients with Alzheimer's disease, 13 subjects with vascular dementia and 31 individuals with Down's syndrome. The frequency of ε4 allele carriers was significantly increased in the Alzheimer's disease group (χ² = 4.918, P <0.05) but also in the vascular dementia subjects (P <0.01, Fisher's exact test). The established relationship between genotype and age at onset of Alzheimer's disease was not statistically significant in these data. Frequencies of the genotypes in the Down's syndrome group did not differ from those of controls. The results obtained in this sample of the Italian population suggest that the apolipoprotein E genotype may be of limited use in the differential diagnosis of dementia.