Uncovering the Role of the Methylome in Dementia and Neurodegeneration.

Our understanding of the epigenome has advanced dramatically over the past decade, particularly in terms of DNA methylation, a modification found throughout the genome. Studies of the brain and neurons have outlined an increasingly complex architecture involving not just CG dinucleotide methylation but also methylation of other dinucleotides, and modifications of methylated bases such as 5-hydroxymethylcytosine. Different modifications may play an important role in brain development, function and decline; recent descriptions of the effects of aging and neurodegenerative processes such as Alzheimer disease on methylation profiles have ushered in an era of DNA methylome-wide association studies. Rapidly improving technologies and study designs are returning robust results, and investigations of the human brain's epigenome are increasingly feasible, complementing insights gained from genetic studies.