One study finds tissue-specific methylation signatures in the genome; another a similarity between identical twins in DNA’s chemical tagging
Tattoos on the skin can say a lot about a person. On a deeper level, chemical tattoos on a person’s DNA are just as distinctive and individual — and say far more about a person’s life history.A pair of reports published online January 18 in Nature Genetics show just how important one type of DNA tattoo, called methylation, can be. Researchers at Johns Hopkins University report the unexpected finding that DNA methylation — a chemical alteration that turns off genes — occurs most often near, but not within, the DNA regions scientists have typically studied. The other report, from researchers at the University of Toronto and collaborators, suggests that identical twins owe their similarities not only to having the same genetic makeup, but also to certain methylation patterns established in the fertilized egg.
Methylation is one of many epigenetic signals — chemical changes to DNA and its associated proteins — that