Familial Alzheimer's disease: site of mutation influences clinical phenotype.

Alzheimer's disease (AD) is caused by multiple genetic and/or environmental etiologies. Because differences in the genetically determined pathogenesis may cause differences in the phenotype, we examined age at onset and age at death in 90 subjects with dominantly inherited AD due to different mutations (amyloid precursor protein, presenilin-1, and presenilin-2 genes). We found that among patients with dominantly inherited AD, genetic factors influence both age at onset and age at death.