a region >500 bps with >50% CpG content unitless
||Human Homo sapiens
||Bernstein D, Golson ML, Kaestner KH. Epigenetic control of β-cell function and failure. Diabetes Res Clin Pract. 2016 Nov 21 123: 24-36. doi: 10.1016/j.diabres.2016.11.009. p.26 right column bottom paragraphPubMed ID27918975
|| M. Zampieri, F. Ciccarone, R. Calabrese, C. Franceschi, A. Burkle, P. Caiafa Reconfiguration of DNA methylation in aging Mech Ageing Dev, 151 (2015), pp. 60–70 DOI: 10.1016/j.mad.2015.02.002PubMed ID25708826
||P.26 right column bottom paragraph: "There are approximately 30 million CpG dinucleotides in the human genome, constituting about 1% of total nucleotide content. A fraction of these CpGs, 1–2%, are clustered in highly dense areas known as CpG islands (CGIs), while the majority of CpGs are dispersed sparsely throughout the genome. A CGI is defined as a region greater than 500 bps with more than 50% CpG content [primary source]. More than half of all CGIs are associated with coding gene promoters, directly regulating gene expression by determining whether or not the basal transcriptional machinery can bind. The vast majority of the genome is highly methylated, which promotes genomic stability by limiting the activity of transposable elements, while certain regulatory elements, including CGIs and enhancers, are usually lowly methylated [ref 28], [ref 29] and [ref 30]."