Abstract
Alzheimer disease (AD) is characterized neuropathologically by neurofibrillary tangles and senile plaques. A key component of plaques is Aβ, a polypeptide derived from Aβ‐precursor protein (APP) through proteolytic cleavage catalyzed by β and γ‐secretase. We hypothesized that sequence variation in genes BACE1 (on chromosome 11q23.3) and BACE2 (on chromosome 21q22.3), which encode two closely related proteases that seem to act as the APP β‐secretase, may represent a genetic risk factor for AD. We analyzed the frequencies of single nucleotide polymorphisms (SNPs) in BACE1 and BACE2 genes in a community‐based sample of 96 individuals with late‐onset AD and 170 controls selected randomly among residents of the same community. The genotype data in both study groups did not demonstrate any association between AD and BACE1 or BACE2. After stratification for APOE status, however, an association between a BACE1 polymorphism located within codon V262 and AD in APOE ε4 carriers was observed (P = 0.03). We conclude that sequence variation in the BACE1 or BACE 2 gene is not a significant risk factor for AD; however, a combination of a specific BACE1 allele and APOE ε4 may increase the risk for Alzheimer disease over and above that attributed to APOE ε4 alone. © 2003 Wiley‐Liss, Inc.