Alzheimer's disease

It evidence that familial Alzheimer disease-1 (AD1) is caused by mutation in the gene encoding the amyloid precursor protein (APP) on chromosome 21q. A homozygous mutation in the APP gene with a dominant-negative effect on amyloidogenesis was found in a patient with an early-onset progressive dementia and his affected younger sister.
Alzheimer disease is the most common form of progressive dementia in the elderly. It is a neurodegenerative disorder characterized by the neuropathologic findings of intracellular neurofibrillary tangles (NFT) and extracellular amyloid plaques that accumulate in vulnerable brain regions. Terry and Davies (1980) pointed out that the 'presenile' form, with onset before age 65, is identical to the most common form of late-onset or 'senile' dementia, and suggested the term 'senile dementia of the Alzheimer type' (SDAT).