Source:http://linkedlifedata.com/resource/umls/id/C1158479
GO: The covalent alteration of one or more nucleotide sites in DNA, resulting in a change in its properties. [GOC:jl, GOC:ma],NCI: Biological processes that involve adding/removing chemical moieties to/from DNA, including methylation, phosphorylation, dephosphorylation, etc.