DNA methylation
From Ganfyd
A form of epigenetic modification that can affect gene expression without direct changes to the genetic code itself.
The most obvious example is the inactivated X chromosome in female cells. Each female invidivdual inherits 2 copies of the X chromosome. To prevent double expression of X chromosome genes, one of the two chromosomes is randomly inactivated during early development. One of the mechanisms is methylation of cytosine residues in DNA. In simple terms, this alters the structure of DNA (but not the coding sequences) and prevents translation of DNA into RNA, effectively silencing the chromosome.
Abnormal methylation can cause inappropriate activation or inactivation of genes and is implicated in diseases such as:[1]
- cancer
- Beckwith–Wiedemann syndrome
- Angelman syndrome
- Prader-Willi syndrome
