Epigenetics

Originally posted 5-25-2006

A few months ago, I read an article that discussed epigenetics. A Medline search defines epigenetics as: epigenetic “factors refer to modifications of DNA and chromatin that ‘orchestrate’ the activity of the genome, including regulation of gene expression.” According to Wikipedia, “Epigenetics is the study of reversible heritable changes in gene function that occur without a change in the sequence of nuclear DNA.” In layman’s terms, it’s the study of why two people with the same DNA can look, feel, and perform so much differently.
It studies why those same two people with the same DNA can be in such different states of health.

So after reading this article, I set out doing some reading to find out just what is going on in the field of epigenetics. Until very recently, it was thought that changes to the DNA structure (insertions, deletions, and mutations) were the only cause of genetic variation. These structural changes to DNA are the very thing that has driven evolution. Epigenetics is the next layer of the onion. Epigenetic modificaitions, or “marks”, can turn a gene on or off, determining whether or not the gene can be used to make a protein. Basically, DNA determines protein structure while epigenetic modifications can determine which proteins are expressed.

These “marks” are passed from parent to child and, since they generally turn genes on or off, can cause diseases by abnormally suppressing or promoting certain genes. In the 1940’s, Dr. Francis M. Pottenger conducted a 10-year study using 900 cats to determine the effects of food on the body. What Dr. Pottenger noticed was that over the course of four generations, cats on a cooked food diet became progressively more diseased over three generations to the point that no fourth generation was ever born. Cats following a raw food diet continued to produce healthy, vibrant kittens. Few pretend to draw a parallel between human nutrition and cat nutrition, but the results of this study are striking, showing that epigenetic changes can cause detriment to the offspring of an organism, as they are also handed down from mother and father to child. These epigenetic changes are often owing to deficient diets, such as those that the unhealthy group of cats followed.

It appears that what we’re talking about is gene expression. Gene expression is what keeps people that are “genetically susceptible” to a disease from actually getting the disease. Most diseases are not inherited; rather a tendency for that disease is passed from parent to child. For instance, many people that have a family history of diabetes, heart disease, or cancer never develop those diseases. The development of the disease is dependent on gene expression. So what drives gene expression? Environmental factors. And what are the environmental factors that can be most easily controlled? Nutrition and exercise! Basically, even though someone may be susceptible to something due to epigenetic inheritance from their parents or epigenetic markers placed throughout their life, by taking care of themselves, they can overcome these diseases.

So there should be some interesting stuff coming down the pipe as scientists work to map the epigenome. Johns Hopkins has recently opened a center dedicated to the study of epigenetics. Of course, epigenetics will probably be rejected by the mainstream as it will require people to take responsibility for their lives. Epigenetics means that people’s actions can not only affect them, but can also determine the health of their children and grandchildren years down the line. People prefer to blame their genes rather than their own lifestyle for all of their ills. If you weren’t born with a disease (such as Downs Syndrome or Type I Diabetes), it is most likely your fault if you develop it. However, for all people that plan to have kids in the future, know that your actions, your lifestyle, the things you eat (and things you don’t eat), and your exercise (or lack thereof) may unnecessarily make your offspring more susceptible to certain diseases.

There is good news though: epigenetic modifications are reversible. While you can’t go back to your childhood and make your parents treat you better or un-experience a tragic event, you can manage your stress, diet, and exercise regimens to correct genes that have been altered. So follow a good exercise program, maintain a healthy diet, supplement with some Cod Liver Oil or Fish Oil, and limit your exposure to environmental toxins and stress as much as possible. If you don’t care about yourself, at least care about those (unborn) that will share your DNA for years to come.

References
Backgrounder: Epigenetics and Imprinted Genes
More on Pottenger’s Cats