Epigenetics literally means “above” or “on top of” genetics. It refers to external modifications to DNA that turn genes “on” or “off.” These modifications do not change the DNA sequence, but instead, they affect how cells “read” genes.
Scientists now think epigenetics can play a role in the development of some diseases. For instance, an epigenetic change that silences a tumor suppressor gene – such as a gene that keeps the growth of the cell in check – could lead to uncontrolled cellular growth. Another example might be an epigenetic change that ‘turns off’ genes that help repair damaged DNA, leading to an increase in DNA damage, which in turn, increases disease risk.