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alzheimersdisease_CD - all lead to a relative excess in the...

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SAMMY J Alzheimer’s Disease: Definition: Alzheimer disease is the most common cause of dementia; an acquired cognitive and behavioral impairment of sufficient severity that markedly interferes with social and occupational functioning neurofibrillary tangles (NFTs) and senile plaques (SPs) at the microscopic level; and cerebrocortical atrophy, which predominantly involves the association regions and particularly the medial aspect of the temporal lobe. NFT s and SPs are the “universal markers” of Alzheimer’s disease Familial forms of Alzheimer disease account for less than 7% of all cases of Alzheimer disease , with most cases being sporadic (ie, not inherited). Mutations in genes coding for 3 proteins unequivocally cause Alzheimer disease. These genes ( for amyloid precursor protein [APP, on chromosome 21], for presenilin I [on chromosome 14], and for presenilin II [on chromosome 1])
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Unformatted text preview: all lead to a relative excess in the production of the stickier 42-amino acid form of the beta-amyloid peptide over the less sticky 40-amino acid form. This beta-pleated peptide is postulated to have neurotoxic properties and to lead to an incompletely understood cascade of events resulting in neuronal death, synapse loss, and the formation of neurofibrillary tangles (NFTs) and senile plaques (SPs) among other lesions. Nonetheless, mutations accounting for less than half of all cases of early-onset Alzheimer disease have been found. Other than the ApoE epsilon 4 genotype, no polymorphisms in other genes have been consistently found to be associated with late-onset Alzheimer disease. http://emedicine.medscape.com/article/1134817-overview...
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