Genetic markers in the diagnosis of Alzheimer's disease.

Abbreviations: AD, Alzheimer's disease; AbetaPP, amyloid beta protein precursor; BACE, beta-site AbetaPP cleaving enzyme; PS1, presenilin-1; PS2, presenilin-2; APOE, apolipoprotein E; LRP, low density lipoprotein receptor-related protein; SNPs, single-nucleotide polymorphisms; A2M, alpha-2-macroglobulin. Alzheimer's disease (AD) is the most common neurodegenerative disorder associated with dementia in the elderly population. Its clinical symptoms are manifest with increasing prominence during mid- to late stages of adulthood. In the absence of precise biological indicators that precede or accompany the cognitive decline, diagnostic confirmation of AD requires postmortem detection of histopathological characteristics such as amyloid plaques, neurofibrillary tangles, and extensive cortical atrophy. While the etiology of AD remains incompletely understood, it was recognized early on that the observed familial aggregation of AD implied the presence of one or more inherited susceptibility markers that could be useful in diagnosis and treatment. To date, genetic analyses of these pedigrees have resolved four independent genetic loci linked with inherited susceptibility to AD.