Amyloid β peptide (Aβ) is one of the hallmarks of Alzheimer's disease (AD). Aβ is a major constituent of extracellular plaques and is derived from the proteolytic processing of the β-amyloid precursor protein (APP). The β -site APP cleaving enzyme (BACE1) is a candidate risk factor for AD because of its involvement in generating Aβ. Its gene is located on chromosome 11q23.3.

The aim of this study was to investigate the BACE1 exon5 C786G polymorphism in AD and healthy control subjects and correlate it with the apolipoprotein E (ApoE) 4 allele status.

Blood was collected from 180 patients with AD and 102 healthy control subjects. The diagnosis of probable AD was based on NINCDS-ADRDA criteria. DNA was extracted by Roche kit. The ApoE and BACE1 polymorphisms were genotyped by RFLP-PCR. The results were analyzed by SPSS program.

There was a higher frequency of ApoE 3/4 genotype and ApoE 4 allele occurrence in AD patients (33%) than in the controls (10%). Regarding BACE1 C786G polymorphism there were no statistically significant differences between the investigated groups in the genotype and allele frequencies. In the presence of ApoE 4 allele the BACE1 GG and CG genotypes occurred in higher frequency in AD (10.2% and 22.2%) than in the control (2.0% and 5.1%) group.

These results suggest that BACE1 gene polymorphism itself is not associated with AD, but in the presence of ApoE 4 allele the GG and CG genotypes might be risk factors in the development of AD.

Supported by:ETT19804/2006, OTKA T046152/2004, K60589/2006.