[Apolipoprotein E 4 gene is a risk factor for Alzheimer's disease]

To study the association of Alzheimer disease (AD) with apolipoprotein E (ApoE) epsilon 4 allele and to find the biological peripheral markers for the laboratory diagnosis of AD.

107 patients with AD, 68 patients with vascular dementia (VD) and 74 sex- and age-matched non-demented healthy individuals (NDC) were collected. DNA from patients and healthy individuals was extracted from peripheral blood samples with the phenol-chloroform procedure and ApoE was investigated with the methods of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP).

The frequency of epsilon 4 was significantly higher in AD than that in VD and NDC and there was no difference in the frequency of epsilon 4 between VD and NDC. The age at onset of the disease in the group carrying two epsilon 4 alleles was significantly younger than that in the group with one epsilon 4 allele in AD. Moreover, in comparison with AD patients without epsilon 4 allele, the age at onset in the group with one epsilon 4 allele was younger. Patients with epsilon 4 or without epsilon 4 allele in VD patients did not differ significantly in age at onset. Meanwhile, 3 familial AD cases were found, all carrying epsilon 4 allele.

AD and ApoE4 were closely related. ApoE epsilon 4 was a dangerous factor of AD and ApoE 4 allele made contribution to the heterogenicity of AD.