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Genetic Testing: Promises and Pitfalls

Genetic Testing: Promises and Pitfalls

Technology advanced greatly over the course of the twentieth century. It is difficult today to recall that half-a-century ago television was in its infancy. Jet powered aircraft were experimental. Business computers were not yet in use. Manual typewriters were the state of the art in written communication and radios were powered by vacuum tubes. Dick Tracy was communicating via two-way wrist radio, but his readers could never have imagined the complexity of today’s cellular phones that deliver the power of the Internet on the go.

In 1950 almost nothing was known about the genetic basis of illness. In 1953 Watson and Crick rocked the scientific world with the announcement that they had discovered and defined the double helix structure of DNA, the compound that carries the instructions for maintaining and reproducing life.

By the mid 1970s methods to determine the sequence of amino acids in DNA had been developed. This laid the foundation for the Human Genome Project, an international undertaking of monumental proportions, which sought to determine the sequence of the approximately 3 billion base pairs (the letters of the DNA message) in the 23 human chromosomes.

All data gathered by the Human Genome Project was posted on the Internet as it became available. This free and immediate dissemination of scientific information was unprecedented in its scale.

In April 2003, two years ahead of schedule, the Human Genome Project was declared complete. The project, in effect, wrote a book containing the letters of the human gene sequence. It did not, however, determine how to read the words in the book. Research to accomplish this is ongoing. Much of this is focused upon identifying which genes are related to disease states. More than 1,800 “disease genes” have been discovered, and over 1,000 genetic tests are now available for assessment of a person’s relative risk of developing diseases or to aid in the diagnosis of specific disease states.

In 2005 a “Hapmap”, a catalog of common gene variations, was published. This has accelerated the search for genetic markers of disease risk.

The cost of running all of the available tests on an individual would be cost prohibitive, but several entities have emerged that offer screening for a limited number of traits and conditions.

For a fee it is possible to obtain a report detailing a number of individual traits such as hair and eye color, alcohol flush reaction, and ear wax type. (I can’t help but wonder why someone would require a genetic test to determine what should be obvious by simple observation. Perhaps we have reached a point where only someone with Sherlock Holmes’ intellect and powers of observation is capable of noting that a friend’s face turns bright red after drinking a glass of wine.)

It is also possible to learn whether one is at increased risk of developing a wide array of diseases including diabetes, emphysema, Lou Gehrig’s disease, and Alzheimer’s disease. A screen looking for a genetic predisposition to skin, bladder, breast, colorectal, lung, thyroid, or prostate cancer or leukemia is available.

Some of the genetic screening services currently available are 23 and Me, deCODEme, and Navigenics. Prices range from less than $200 for a focused cardiovascular risk screen to $2500 for a profile that reports the genetic risk for approximately 30 disease states and offers personal genetic counseling.

The decision to pursue genetic screening should be made only after carefully considering the implications of such testing. Most health screening tests are performed to detect diseases early in their course. Genetic testing, however, is done primarily to determine whether an individual has a predisposition to develop a particular condition. A positive finding does not indicate that the person being tested has the disease, nor that he or she will ever have the disease.

It is my opinion that no test should be performed unless one is prepared to change one’s direction based upon the results. If an individual has adopted a wellness strategy that maximizes the chance of a long and productive life there is little or nothing to be gained by requesting genetic code screening. The same is true if the individual has no intention of making any lifestyle changes regardless of what the results reveal. If, however, a person is willing to change habits if the results show that there is a significant risk of developing a life-threatening or disabling disease, investing in the test may be worthwhile.

The greatest risk of pursuing genetic testing is the possibility that the knowledge that one is at increased risk of developing a particular disease will become a self-fulfilling prophecy. The comedic actor John Candy is an example of this danger. Mr. Candy did not need to obtain a genetic profile to know that he was at risk for dying of a heart attack. His father had died of a heart attack at age 35, when John was only 5 years old. His grandfather had also died of a heart attack.

Knowing that he had a family history of heart disease did not motivate John Candy to take steps to minimize that risk. Instead he adopted a philosophy of living hard and fast so that he could experience as much as possible before his own heart attack occurred. He became a heavy smoker who also drank and ate to excess. He died of a major heart attack at age 42.

Another factor to consider is what may be done with the information. I have always been reluctant to attach names to symptoms when the diagnosis is in doubt. Diagnostic labels have consequences. Having a medical diagnosis may make it difficult or impossible to purchase life or health insurance. It may reduce your ability to obtain employment. Documentation of genetic health risks may ultimately proof disadvantageous. In our computerized age it is impossible to guarantee confidentiality. While laws have been passed that prohibit discrimination on the basis of genetic screening results it is still possible that results could be used against an individual should they fall into the wrong hands. This is a risk that should be taken into account when considering comprehensive genetic screening testing.

In my opinion one of the most absurd uses of genetic testing is that promoted by GeneWize Life Sciences. The company specializes in producing “personalized nutritional supplements” based upon DNA analysis. Each client is sent a DNA collection kit. The swab of the cheek is sent back to the company, which claims that by evaluating the person’s genetic code they can determine the precise levels of nutrients the individual should be taking to assure good health. The company states that they are able to do this by combining 100 specific nutrients in 177,000 different ways.

There are several challenges with the GeneWize approach to nutritional supplementation. The first is that the precise number and level of nutrients required by the body to deal with specific challenges are unknown. It is clear, however, that there are well over 100 nutrients needed for the body’s ongoing repair and maintenance tasks. To suggest that the precise level of each essential nutrient can and should be individualized is patently ridiculous.

Secondly, the search for genetic markers of disease is ongoing. Even if it were possible to precisely provide the exact number and amount of key nutrients necessary to prevent one of the diseases for which genetic markers currently exist there would be no guarantee that those same nutrients would be protective for disease states for which genetic markers have not yet been identified.

Thirdly, environmental exposures play a far greater role in disease development than do genetic factors. To base the decision of what levels of nutrients are required upon one’s genetic code is a recipe for disaster. For example, an individual who has no genetic predisposition to heart disease but who smokes two packs of cigarettes daily, eats a diet high in saturated and trans fats, and is a couch potato is at much greater risk of experiencing a heart attack than someone who has a genetic predisposition to coronary artery disease but who has never smoked, makes wise dietary choices and remains physically active. Both require antioxidant support, but the smoker’s needs are much greater.

Finally, tailoring a person’s nutritional support to address specific genetic predispositions will not provide the comprehensive support needed to allow the body to address the many challenges it will face that have no clear genetic profile. It has been demonstrated, for example, that antioxidant nutrients can help the body protect itself from non-ionizing radiation, something that did not exist to any significant degree until the mid-twentieth century and will therefore have no marker in the genetic code.

Enough is known about the breadth and depth of nutritional supplementation required to support the body’s ability to address the mechanisms that lead to premature aging and predispose to all disease development. These include free radical damage, inflammation, loss of methylation potential, and mitochondrial decline. When these challenges can be faced successfully the conditions to which an individual is genetically predisposed will rarely manifest. This has been shown by decades of success. Attempting to address health challenges by focusing upon one’s genetic code is a step backward, not a major scientific advance.

Years ago Kenny Rogers introduced a hit song called The Gambler. One of the verses contained some sage advice:

Now ev’ry gambler knows that the secret to survivin’
Is knowin’ what to throw away and knowing what to keep.
Cause ev’ry hands a winner and ev’ry hands a loser,
And the best that you can hope for is to die in your sleep.

Each of us has been dealt a genetic hand; some hands are better and some are poorer. Nevertheless, every hand’s a winner and every hand’s a loser. In life, as in poker, the cards you have been dealt are not nearly as important as how you play the game. As the gambler told the young man on the train - “If you're gonna play the game, boy, ya gotta learn to play it right.”

We know a great deal about how to successfully play the game of life. How you choose to live will play a much greater role in determining whether you die peacefully in your sleep following a rewarding day pursuing things you enjoy than the genes you were dealt.

© 2009 Wellness Clubs of

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