Epigenetic alteration associated with increased risk of breast cancer
 

Monozygotic twins have the same genome, that is, the same DNA molecule in both siblings. Despite being genetically identical, both twins may have different diseases at different times. This phenomenon is called "twin discordance". But how can people who have the same genetic sequence present different pathologies and at different ages? The explanation partly lies in the fact that the chemical signals added in the DNA to "switch off" or "switch on" genes can be different. These signals are known as epigenetic marks.

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