Alzheimer's disease

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For early-onset Alzheimer's, more than 150 mutations of the presenilin 1 PS1, presenilin 2 PS2, and amyloid precursor protein APP genes have been associated with autosomally dominant inheritance (of early-onset ALZ).

The most notable late-onset SNPs are

Most genes other than ApoE and TREM2 have much smaller individual effects on the risk for developing Alzheimer's disease, however, numerous such reports have been published (see below).

APOE4 homozygosity (gs216) is associated with increased risk of Alzheimer's PMID 15956169. However, according to some studies, ApoE4 differences only affect cognition significantly after age 60. The memory changes that occur from 20 to 60 may not be connected to ApoE4 at all. See People at genetic risk for Alzheimer's age mentally just like noncarriers. Other studies, however, show brain changes and decreases in cognitive function in epsilon-4 carriers starting at an early age.

Conversely: although SNPs in the MAPT gene do not influence the risk of having Alzheimer's, they appear to lead to increased MAPT mRNA production, which leads to increased levels of the tau protein in cerebrospinal fluid, which ultimately led to an earlier age of onset of Alzheimer symptoms (in those who eventually developed Alzheimer's). So if - and only if - a person is fated to develop Alzheimer's for other reasons, then these MAPT SNPs are correlated with exhibiting symptoms sooner. PMID 18541914

One hypothesis is that genes relevant to viral infection, and in particular herpes simplex virus (HSV-1) infection, may increase the risk for Alzheimer's, especially in individuals already predisposed to Alzheimer's, such as those carrying ApoE4 alleles. PMID 16406033 In connection to this hypothesis, rs2254958, a SNP in a gene influencing HSV-1 infection, has been found in higher frequency in certain AD patients. PMID 17420072

Two studies (Caffeine Reverses Cognitive Impairment and Decreases Brain Amyloid-? Levels in Aged Alzheimer's Disease Mice and Caffeine Suppresses Amyloid-? Levels in Plasma and Brain of Alzheimer's Disease Transgenic Mice published in the July 2009 issue of the Journal of Alzheimer's Disease point to caffeine as reducing a protein (beta amyloid) that is a sign of Alzheimer's disease. More recent studies (such as "High Blood Caffeine Levels in MCI Linked to Lack of Progression to Dementia") have lent further support to this finding.

List of related genes[edit]

Links to external information[edit]

HP:0002511