Encyclopedia of Cancer

2011 Edition
| Editors: Manfred Schwab

Hypomethylation of DNA

  • Miguel A. Peinado
Reference work entry
DOI: https://doi.org/10.1007/978-3-642-16483-5_2923

Synonyms

Definition

DNA hypomethylation refers to the loss of the methyl group in the 5-methylcytosine nucleotide. Methylation is a natural modification of DNA, and mainly affects the cytosine base (C) when it is followed by a guanosine (G) in mammals ( Methylation). The term hypomethylation can be applied to describe the unmethylated state of most CpG sites in a specific sequence that is normally methylated, or as a general phenomenon affecting the bulk of the genome; this is a decrease in the proportion of methylated versus unmethylated cytosines.

Characteristics

In human, DNA methylation mainly occurs at CpG sites. Up to 80% of all CpG sites in human DNA are methylated. However, this methylation occurs primarily in areas where CpG density is low, or at repeat DNA sites, such as Alu elements. CpG islands are regions where CpG density is high and most of them are unmethylated. Patterns of DNA methylation have been linked to control of gene...

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References

  1. 1.
    Ehrlich M (2002) DNA methylation in cancer: too much, but also too little. Oncogene 21:5400–5413PubMedCrossRefGoogle Scholar
  2. 2.
    Feinberg AP, Tycko B (2004) The history of cancer epigenetics. Nat Rev Cancer 4:143–153PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  1. 1.Institute of Predictive and Personalized Medicine of Cancer (IMPPC)Badalona, BarcelonaSpain