Definition
A type of epigenetic modification where methyl groups are added to DNA.
Use in clinical context
Methylation acts to stop transcription of genes. It does this by methylating sites next to genes that would ordinarily be involved in initiating gene transcription. When methylation is altered, it can contribute to whether a gene is transcribed or not.
Unlike in normal cells, in cancer cells methylation is often altered, causing changes in gene expression and contributing to disease progression. For some individuals, it is appropriate to treat their cancer with drugs targeting methylation.
Methylation can also be responsible for non-cancer genetic conditions, for example, some cases of Prader-Willi syndrome are the result of inheriting two methylated copies of part of chromosome 15.
It can be important to consider more than the changes to the DNA sequence when searching for the cause of an individual’s condition. Epigenetic changes, such as methylation, should also be considered and tested for if appropriate.
Related terms
Epigenetics | Deoxyribonucleic acid (DNA) | Gene | Transcription
