Fig. 3

Diagram showing the mechanism of DNA methylation (DNAm). DNAm often takes place at the 5-carbon location of the cytosine (C) base, mainly in the CG position (CpG loci), which are unevenly allocated throughout the genome and to a lesser extent in non-CG context. Several DNA methyltransferases (DNMTs) are responsible for ligating methyl groups to DNA. The methyl donor is S-adenosylmethionine (SAM). SAM is converted to S-adenosylhomocysteine (SAH)