Source:http://linkedlifedata.com/resource/umls/id/C2613366
GO: An increase in the epigenetic methylation of cytosine and adenosine residues in a CpG island in DNA. CpG islands are genomic regions that contain a high frequency of the CG dinucleotide and are often associated with the transcription start site of genes. [GOC:jl, Wikipedia:Cpg_island]