DNA methylation in Alzheimer's disease: In brain and peripheral blood

Alzheimer's disease (AD) is the most widespread neurodegenerative disorder and has caused a major global health concern with the aging of the population. Recent studies have suggested a role for epigenetic mechanisms in AD. DNA methylation is a vital component of the epigenetic machinery which is the best-studied example covered by epigenetics. Studies of DNA methylation have been proceeded in different brain samples, peripheral blood and both in AD. But little is known about whether the easily accessible tissue, peripheral blood, can be used to address questions about epigenetic variations in brain which would normally be inaccessible. Here, we provide a systemic review of the DNA methylation as well as hydromethylation profiles in in human brain and peripheral blood samples of AD. We found that APP gene was the only one that consistently hypermethylated in both brain and peripheral blood, which suggested it could be the most promising diagnostic blood marker of AD in the future, and more energy need to be devoted to studies of DNA methylation after cell classification.