Epigenetics – Lay Version

Epigenetics literally means ‘upon’ genetics and describes a series of biological processes that affect how our genes behave. Epigenetic processes play a vital role in early and healthy development and are responsible for the cellular diversity throughout our bodies, i.e. whilst all of our cells possess an identical genetic code they both appear and function differently, e.g. our cells in our skin look different and perform a different purpose to those in our bones. This is possible because epigenetic mechanisms turn specific sets of genes ‘on’ and ‘off’ and this determines the cell type. Genes – stretches of DNA that encode a specific protein – are switched ‘on’ and ‘off’ through epigenetic control of gene accessibility, e.g. genes within exposed areas of DNA are considered active (switched ‘on’) whilst those in more densely compacted regions are considered to be inactive (‘switched off’). Epigenetics is therefore important in maintaining health but can become deregulated in diseases including cancer. Click here for a video explaining the concept of epigenetics and cancer.

Epigenetic mechanisms are collectively referred to as the ‘epigenome’ and include one of the best studied epigenetic processes called, ‘DNA methylation’. DNA methylation has been shown to be dramatically altered in cancer tissue and can often be found in normal tissue in areas adjacent to cancer. Furthermore epigenetic mechanisms are responsive to our environment which in turn affects our risk to develop cancer and other disease. Our environmental exposures during development in the womb and after birth, as well as our diet and lifestyle all affect our cancer risk (See Figure 1). Accumulation of epigenetic changes as we age could therefore explain the vast majority of cancer that occurs in women who do not carry a predisposing genetic mutation and furthermore represent valuable biomarkers for disease risk.