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Epigenetics

Inherited traits caused by changes in a chromosome without alterations in the DNA sequence

By ALEXANDRA HOWARD
   Some days we find ourselves looking at family photos, examining the similarities and differences in each member and pointing out the apparent inheritances. Other days we find ourselves realizing how similar we act to our relatives in certain situations and even express frustration towards them for passing down diabetes or other diseases, preventing us from enjoying all that life offers. 
    We know who we are related to and how we relate to them, but recent research and discoveries in the new field of epigenetics take us deeper into the complex realm of inheritance and how powerfully sensitive our bodies are, leaving us with so many thought-provoking possibilities that will forever change our perception of who we are and the future of our lives.
Over the past few years, epigenetics, meaning “above the genome,” has become a new explanation and application to studying inheritance and biotic destiny. Ten years ago, scientists believed that the Human Genome Project was the key to mapping our DNA sequence and how the human body is constructed at a molecular level, ultimately finding cures for diseases through their genetic components with the concept of “one gene, one disease.” However, as the project continued, scientists discovered that the number of human genes was not proportional to our complexity. So what was missing?—an astounding method of dictation called epigenetic tagging. This concept can be best compared to our use of a light switch. We turn a light “on” or adjust the brightness of a room if it is too dark while epigenomes decide whether or not to turn a gene “on” or “off” based on the habits of the particular person and if there has been a dramatic change in his or her environment or diet. 
    These tags were believed to be 
removed once the egg and sperm met to wipe the slate clean so that the potential child would only inherit the core sequence of DNA from the mother and father—until it was discovered that certain tags 
remained, passing down genetic edits to children and grandchildren from happenings that their parents or grandparents 
experienced.
    An understanding of how these minor evolutions work can be coherently observed through Professor Marcus Pembrey of University College London and Professor Lars Olov Bygren of University of Umeå’s studies of the population records of Overkalix, a small isolated town in Sweden. In BBC’s 2008 documentary, The Ghost In Your Genes, Pembrey and Bygren explained how these records spanned over hundreds of years with precise details of harvests, allowing them to gather data about many generations. The town's confined location limited residents to an inconsistent food source and they frequently experienced famine that led to an 
unhealthy diet and poor nutrition. 
    After reviewing the records, Pembrey and Bygren found that “the life expectancy of the grandchildren was being directly affected by the diet of the grandparent.” Now that they had noticed a trend, the 
next step was to pinpoint when a “trans-generational” response can be triggered during a lifetime, leading to the incredible discovery of “environmental information being imprinted on the egg and sperm at the time of their formation. The grandmother appeared susceptible while she herself was still in the womb, while the grandfather was 
affected just before puberty.”
    Now that the periods of sensitivity have been discovered, is there any way to reverse the outcome? In 2002, such contemplations were pursued in an experiment documented in The Journal of Nutrition. Geneticists took two female mice carrying the dominant agouti gene (which causes their appearance to become yellow and fat instead of the common brown appearance) and fed them large quantities of B-vitamins and soy before and while they were pregnant. As a constant, they fed another set of agouti gene mothers regular nutrition. The mothers that ate the average diet gave birth to yellow, obese pups. The mothers that were fed the vitamin-altered diet produced pups healthy in shape and brown.
    Another experiment on mice was done again with scientists manipulating agouti alleles (turning them “on”), results in yellow and fat mice. When geneticists turned the alleles half “on” and half “off” for another group of mice, a yellow and brown pigmentation resulted. 
    Seeing that our diet and environment play large roles in epigenetic tagging, is it also possible that our mind, another major asset to our well-being, can contribute? According to an article in the LA Times, concepts such as the placebo effect connect to epigenetics as to how we can “take control over biology.” Is it possible to 
figure out what turns on genes that effect our health poorly or positively and set them to our desired lifestyle to benefit us as well as our children and grandchildren? 
    Additionally, scientists should then be able to manipulate epigenetic tags to 
figure out how to prevent cancer (flip the switch “on” the tumor suppressive gene) or mental disorders (flip the switch “on” for a stress hormone gene). However, diseases and mental conditions are influenced by many different abnormalities that could result in a butterfly effect when changing one thing. If that concept is taken into account at a slow and steady pace, revolutionary advancements can arise.
     Epigenetics began as a study of the role of inheritance in human complexity and has now opened up many possibilities for the future of science and medicine. Josh Clark, a host of the podcast Stuff You Should Know, made a prediction on the show’s epigenetic episode concerning prospects of the field: “Our future and complete understanding of humanity is going to be a combination of sociology and epigenetics.”
    From the details of our grandparents existence to our everyday 
interactions and reactions, epigenetics appropriately refurnishes and renovates the antiquated buildings of the human genome for a more present day setting. There will be maintenance and cleaning 
regularly, even disasters that take much construction to repair, and we may not always be happy with the results along the way. 
However, acknowledging that the capabilities of our body are more powerful and sensitive than we ever imagined can lead to even more discoveries in the amazing field of epigenetics.


Published: October 10, 2010
Issue: November 2010 Arts and Politics Issue