Epigenomics is the study of the epigenome, which is a multitude of chemical compounds that direct the functioning genome as a whole. These compounds bind to the DNA to activate or deactivate specific genes in the genome, thereby altering the way that it behaves. As a result, the epigenome may play a role in the regulation of protein production in some cells of the body.
The process of epigenomic compounds binding to DNA and exerting their effect on its function is referred to as “marking” the genome. The presence of these marks does not affect the sequencing of DNA but alters the function of the DNA.
There are two types of marks of an epigenomic compound, which are:
- DNA methylation: methyl groups of proteins can attach to the bases of DNA at specific receptor sites to directly affect the DNA in a genome. The binding of the methyl group can switch the gene on or off and lead to a change in the way the DNA interacts with other proteins.
- Histone modification: proteins can attach to histone proteins, which usually exist within the genome because DNA wraps around them. This changes the way that other proteins in the area interact with the region of DNA, to affect the DNA in the genome indirectly.
The epigenomic compounds can be passed on from one cell to another during the cell replication process to mark the next generation of cells. This mean that they are heritable, but via cell meiosis and mitosis.
Changes to the epigenome
In the human genome, there are two copies of each gene – one from each parent. Epigenomic compounds play a role in determining which gene is active at any one time. Imprinting is the pattern that naturally regulates which copy of the gene is active at any one time and can be altered by the epigenome
Some health conditions are thought to be associated with a change in the imprinting of the genome. This includes conditions such Beckwith-Wiedemann syndrome, Prader-Willi syndrome and Angelman syndrome. Therefore, information that epigenomics can reveal about the nature of epigenomic imprinting and its effect on the human genome could be applied in medical practices i.e. diagnosis and treatment of these and related conditions. Some changes to the epigenome are also associated with an increased risk of cancer.
It is possible for the epigenome to change throughout the lifetime of an individual. This adjustment can be a normal response to environmental exposures and be a feature of human adaptability, but it may also have the potential to cause disease. Some factors that may lead to changes in the epigenome to cause disease include smoking, diet and infections.
Research about the epigenome
Researchers are currently attempting to map the locations and function of the various chemical marks of the epigenome, which can affect the function of DNA. Epigenomics is an important part of the research efforts to improve our understanding of human health and disease.
It is a new field because it was only recently discovered that the surrounding chemical compounds can change the way the genome functions. In the past, the sequence of DNA has been the core of genomic research. In the future, it is hoped the epigenomic maps could provide information to health professionals about the health of an individual and aid in predicting their risk of developing certain health conditions or gauge their response to medical therapies.
Reviewed by Afsaneh Khetrapal BSc (Hons)