I am honored to write for the Calgary Herald every month. This month I decided to cover a topic which we will hear much more about in future. Its an exciting concept—that our genes do not have to determine our destiny.
A few years ago the American Academy of Pediatrics announced that one of their four top priorities will be epigenetics. At that time I was curious as to how many pediatricians—both in Canada and the USA— were able to explain to the public what the science of epigenetics may involve.
Very few doctors felt fully comfortable, explaining epigenetics at that time.
Recently more doctors, and an ever-increasing number of journalists, have become fascinated by this relatively new science.
PBS aired a piece on epigenetics www.pbs.org/wgbh/nova/body/epigenetics.html) Time magazine also ran a cover story on Jan 18, 2010 on the way our DNA is expressed.
When the genome project was launched and completed, some experts used the analogy of explorers who now finally had a map of the lie of the land. The mapping of our DNA and sequence of our our genes were seen a major breakthrough at that time. Epigenetics may trump that discovery.
Popular media has used the analogy of how computers function to explain epigenetics: the genome is the hardware and epigenetics is the software telling the hardware how to function. Another frequently-used analogy is that some genes are like a voice expressing itself: it may whisper, talk our shout.
How this hardware—software situation unfolds, remain very complex. When a chemical tag (methyl group), attaches itself to a gene that process is called DNA methylation. It influences the way the gene is regulated and expressed. Genes also coil themselves around proteins (histones) and that process may be dependent on epigenetics.
The determinants of this methylation process are numerous: the way we eat, exercise what we drink, how much stress we experience, the medications we take and where we grow up are but a few factors.
When identical twins are born and their genes compared soon after birth we are impressed by the similarities in genes. However, when studying those same twins years later, their genes are not the same anymore —partially due to lifestyle differences and the environment versus genes interaction.
The old expression “Genes make you who you are” simply is wrong or at best partially correct. It is not the whole story.
The implications of this science are huge in virtually every area in pediatrics, but especially so in areas of cancer, mental health, allergies and obesity.
Dr Randy Jirtle’s work at Duke University on Agouti mice remains one of the more popular examples of how epigenetics may influence our obesity genes. By feeding the pregnant mice a diet rich in methyl groups, the offspring were different—thin brown mice were born, as opposed to fat yellow mice in a control group. (See the above PBS link for a video and interview with Dr Jirtle)
The story does not end there though, because when genetic regulation changed, the next generation got affected. One can speculate that when an obese child gets into trouble with inflamed liver, diabetes or high cholesterol, that when such a person grows up, and procreates, he or she will pass on genes to the offspring that may have negative effects. Multiple generations may be impacted by poor choices made in childhood.
The importance of timing of gene regulation will remain a huge mystery for the immediate future. For now we know that a fetus or young baby subjected to toxic stress may have their genes impacted and changed though a process of epigenetics.
Some experts speculate that the rise in autism and other mental health disorders may in part be due to epigenetics.
For example, a hormone oxitocyn in children with autism may have been regulated via epigenetics, but exactly how this happened and when it happened can be debated. It is as if there is smoke, but experts cannot agree on the size of the fire.
At the prestigious MD Anderson cancer center in Houston scientists have already used epigenetics in treating some cancers successfully. Recently Ms. Jolie’s decision to have a double mastectomy based on her genetic predisposition to breast cancer made headlines. It unfortunately left the impression that if a woman carries a breast cancer gene she is doomed—the role of epigenetics was rarely mentioned.
In the USA, the NIH has sponsored further research in this important and emerging field. This research is complicated and expensive. It is a work in progress, but the bottom line to pediatricians and their patients should be simple: by adopting healthy lifestyles early in life and sustaining healthy choices we can perhaps impact the way our “bad” genes express themselves.
Common sense is not common—if it were we will all get enough sleep, eat more fruits and vegetables, avoid smoking whatever, and get our daily dose of fresh air, enjoying the exercise we enjoy the most.
Epigenetics also reminds us that unhealthy lifestyle choices are not only about us; it is also about future generations and how much society will pay to care for obese patients or deal with an ever-increasing population of mental health challenges.
DR. NIEMAN IS A COMMUNITY PEDIATRICIAN AND A MEMBER OF THE CANADIAN PEDIATRIC SOCIETY AND THE AMERICAN ACADEMY OF PEDIATRICS.
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