DNA methylation
DNA methylation is a biological process by which methyl
groups are added to the DNA molecule. Methylation can change the activity of a DNA
segment without changing the sequence. When located in a gene promoter, DNA methylation typically acts to repress gene transcription. In mammals, DNA methylation is essential for normal
development and is associated with a number of key processes including genomic
imprinting, X-chromosome
inactivation, repression of transposable
elements, aging, and carcinogenesis27.
