I am going to step away from traditional genetics for a post to discuss something that affects genetic expression but with which most people are generally unfamiliar: epigenetics. Epigenetics are heritable changes in gene expression not resulting from DNA changes. There are several mechanisms by which epigenetics take place, for instance DNA methylation is a process where a methyl group is added to an A or C rendering those base pairs inaccessible for gene activity. I will not delve into all the mechanisms, as that would make for an extremely long post, but rather take a little time to explain some of the effects as well as interesting recent epigenetic findings.

Epigenetics are important in development, as it is the process by which specific genes are turned off to create different tissues during embryogenesis. As epigenetically modified genes are turned off, it is also a source of disease that may resemble classical genetic diseases. Notable examples of this are Prader-Willi and Angelman syndromes. These two rare genetic diseases are actually the result of loss of genetic expression of the same region of chromosome 15, so one might ask how do you end up with two differing disorders; the answer lies in parental, sex specific epigenetic modification. The region contains genes differentially, epigenetically modified on paternally and maternally inherited chromosomes. Loss of the region inherited from the mother results in Angelman syndrome but inheritance from the father results in Prader-Willi syndrome. For a more in-depth look see http://www.nature.com/scitable/topicpage/imprinting-and-genetic-disease-angelman-prader-willi-923.

Lastly, epigenetic modifications may result from environmental influence. Environmental exposure, such as a person’s diet, can effect expression of their genes. Additionally, recent findings show that environment also affects epigenetic modification passed on to offspring. A Nature Communications publication in April found that a woman’s diet at the time of conception actually affects what genes will be epigenetically modified in her baby (http://www.technologynetworks.com/Genomics/news.aspx?ID=165262). While much research remains to understand the implications of these changes, significant changes in methylation levels were associated with differing nutrient levels and body mass index. These findings underpin the importance of further studying epigenetics as a mechanism to possibly explain some of the ‘nature vs. nurture’ debate.