negative regulation of gene expression via chromosomal CpG island methylation https://github.com/geneontology/go-ontology/issues/24543 https://github.com/geneontology/go-ontology/issues/24711 biological_process DNA hypermethylation of CG island DNA hypermethylation of CpG island hypermethylation of CpG island negative regulation of gene expression via CpG island hypermethylation GO:0044027 negative regulation of gene expression via chromosomal DNA cytosine methylation negative regulation of gene expression via CpG island methylation maintenance of DNA methylation negative regulation of gene expression via chromosomal CpG dinucleotide methylation An epigenetic gene regulation mechanism that negatively regulates gene expression by methylation of cytosine residues in chromosomal CpG islands. CpG islands are genomic regions that contain a high frequency of the CG dinucleotide associated with the transcription start site of genes. negative regulation of gene expression via chromosomal CG dinucleotide methylation epigenetic regulation of gene expression via CpG island hypermethylation negative regulation of gene expression, epigenetic