As medicine drags itself out of its dark and dangerous past, we have come to believe that the discovery of DNA and the mapping of the human genome will finally make it clear how to live a healthy life and how to correct any genetic problems we may have adopted at conception. Genetics was to be our new saviour.
Alas, the more we learn about genetics the more confused we become. The genetic map is clear and becoming better defined as more scientists work with it to find exactly what each gene does and how it cooperates with others to produce the beings we are. But it doesn't always tell us where we are going, as a good map should.
It turns out there is more to DNA than two sets of genes clustered on 24 sets of chromosomes. Genes only comprise about half of the mass of a chromosome.
We know that each gene expresses itself by producing a protein. We know that the proteins act as switches to turn on and off bodily functions from the time of conception until we die. We know that, somehow, the genes know when to express themselves (turn their switches on) and when to remain quiet (most of the time the switches are off).
What we didn't know was how the switches get flipped and why, even in sets of identical twins, one switch may be turned on at one time in one of them but not in the other. Identical twins, it turns out, are only identical if the switches of each gene turn on and off at approximately the same time. They usually do, but not always, despite the fact that their genetic makeup is identical.
Short parents can produce tall children (well, they begin small). Two brown-eyed parents can produce blue-eyed children, even though the gene for brown eyes is supposedly dominant. Two parents with a gene that has caused both to suffer from a genetically inherited disease may produce a perfectly healthy child.
Male pattern baldness sometimes skips a generation, sometimes two generations. Yet the same genes carry the same factors through all generations of males in the family, even the ones that don't go bald. In other words, even though a person carries a gene that determines he will go bald as an adult, he may not lose his hair.
What we tend to call genetic defects (sources for disease) can be carried through several generations of the same family, though not everyone with the "defect" will suffer from whatever the others get. Then the defect may disappear from the family, apparently spontaneously. Yet in disappearing, the makeup of the genes of the offspring without the defect may be exactly the same as the makeup of the genes of the parents.
Enter the relatively new science of epigenetics. Our genes not only produce proteins, they also carry their protein on their outsides. We wouldn't expect that any outside influence could affect the genes themselves, but it might affect the protein switches on the outsides of the genes.
Epigenetics shows how that happens. Or it plans to in the coming years.
The viability of proteins on the outside of genes determines whether those genes impact our lives positively, negatively or not at all. Those proteins are influenced by how we lead our lives. Whether we smoke, endure stress, eat a healthy diet and exercise can affect those exterior proteins.
Wait, it gets worse. Not only can what we do and how we live affect the expression of our proteins, what our parents did, and their parents before them, even a generation or two before that can affect the expression of our genes through their proteins in our bodies.
In turn, if we do something that affects the proteins of our genes--such as living next to a factory that puffed out lead with its smoke--that changes the proteins on the exterior of our genes and a mother can pass that on to a child she gives birth to years later. Once changed, the proteins can remain in the changed state for several generations.
Unlike genetics, however, which offers little hope--people with certain gene-related diseases give birth to children with the same disease or criminal behaviour tends to follow through generations maybe due to genetic makeup--epigenetics holds out the promise that we can not only change our own lives but the lives of generations that follow us.
If we know that the protein on the exterior of a particular gene in our bodies won't turn on when it's supposed to turn on, we will eventually know enough to be able to change that situation so that it will switch on when it's supposed to. In theory, if we know ahead of time that our genetic makeup says it's likely we will develop some form of cancer, we can take measures to prevent that from happening by manipulating which genetic proteins are allowed to prevail and which are turned off.
The epigenome project--proposed by many scientists in several parts of the world but far from a fact--will make the mapping of the genome seem like child's play. Unlike genetics that tells the makeup of each of our three billion pairs of nucleotide bases in our DNA, each of us has not one but a multitude of epigenomes as the switch of one gene may be on or off in various combinations with others in the body.
Epigenetics holds out real promise for fighting disease and malformations of the body. But once the solutions to our health problems are developed, only following a strict regimen of diet, exercise, lifestyle and prescribed supplements will change what will happen to us. Few potential problems will be thwarted by popping pills alone.
Epigenetics may explain why we have generations of overweight and obese people today because so many of our ancestors did something that changed the expression of certain genes in the past, then we inherited that changed expression. The rise in cases of asthma, autism and Alzheimer's may also be explained when epigeneticists learn more.
The curtain is about to go up on some of health's greatest mysteries.
For further reading on the subject of epigenetics I recommend the following as possibilities:
"DNA Is Not Destiny," Discover magazine, November 2006
"Epigenetics," Wikipedia, http://en.wikipedia.org/wiki/Epigenetics
Landes Bioscience, http://www.landesbioscience.com/journals/epigenetics
Epigenetics News, http://www.epigeneticsnews.com
Turning It Around: Causes and Cures for Today's Epidemic Social Problems, striving to clarify the tough questions of life to make them easier to understand.
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