Molecular genetics of Alzheimer's disease: the role of beta-amyloid and the presenilins.

Alzheimer's disease is the most common neurodegenerative disorder of aging, accounting for an estimated two-thirds of all cases of senile dementia. Epidemiologic studies have failed to resolve any single cause of Alzheimer's disease and suggest a complex etiology, with environmental and genetic factors influencing the pathogenesis. Although the majority of cases are sporadic, a small number display familial clustering. Genetic analyses of these pedigrees have identified four genes that are involved in the development of Alzheimer's disease.