TBO.com - TBO is Tampa Bay Online

Unraveling Genome Has Great Potential, But We're Not There Quite Yet

ADVERTISEMENT

By RAO MUSUNURU

For The Tampa Tribune

Published: January 11, 2009

It may not be the most attractive or appealing definition, but in its strictest scientific sense, life is a common, sexually transmitted, medical condition with 100 percent mortality. At the time we are conceived, we are all programmed to die. Human life is being transmitted through "genes" the same way, since its creation. How well and how long each one of us lives is essentially decided by the genes, if we let nature take its course.

In the most simplistic form, the genes are transmitted through 23 pairs of chromosomes, half of each pair contributed by each parent. The chromosomes are housed in the nucleus of each cell in our body. The chromosomes are made up of DNA. The DNA of each chromosome is encoded into various genes, with spaces in between. DNA directs the synthesis of RNA in the cell. The RNA directs the synthesis of various proteins, for example, enzymes that control all body functions. Almost 99.9 percent of the genetic material is common to all individuals.
Genes are responsible for expression of all the features and characteristics of each person - how one looks, how one thinks, what diseases one may be susceptible for, and how one will respond to an intervention (for example, the response to a treatment and also the side effects of the treatment).

If it is all controlled by the genes, why do we keep stressing the importance of environment (for example, risk factors for a disease, say smoking). Many inherited genetic variations do not express themselves, until exposed to an environmental stimulus, good or bad. Also, many genetic variations (good and bad) occur throughout one's life, as a response to various environmental stimuli including medical interventions, some in a relatively short time of weeks or months. Some of these acquired changes may persist and be passed on to the next generation (for example, mutations).

At this time, for all practical purposes, physicians offer the same kind of treatment options, in various combinations, to all the patients with similar kind of illness. If we know the genetic makeup of an individual and how that will change his or her response to a particular treatment, we should be able to personalize the treatment with customized options for that particular patient for that disease. Right now, this is feasible only for a limited and small number of diseases, including some cancers.

Whereas the potential of analyzing the genetic makeup of an individual on a commercial basis, "to assess the risk of developing a disease, to determine ways to prevent a disease, and to personalize the treatment" is enormous for the future, the future is not quite here.

There are companies that are heavily involved in direct consumer marketing of "genetic testing" that will "decode your genetic information and assess your risk for various diseases" at a cost of a few hundred to a few thousand dollars. Do not be surprised if one of your loved ones will offer one of these services as a gift for your next birthday or Christmas. Also, do not be surprised if your doctor tells you honestly that he or she does not know what all that information means or what to do with all that information. The sales pitch may sound very empowering to the public, but it may not have much clinical utility at this time.

All this new remarkable and impressive technology (capable of deciphering 3 billion basepairs of the human genome) is still a research tool and is not ready for prime time use for individual patients - with a few exceptions, when the particular genetic information is specifically requested by a physician. Many researchers and clinician-scientists, my son included, are working very hard to further unravel the mystery, as it holds a lot of promise for the future in medicine. It will even lead to discovery and development of new better and safer treatment modalities.

Keep faith and consult your physician when in doubt. For physicians, obtaining a good family history still remains the best and cheapest genetic test. For patients, controlling known risk factors still remains the most effective and the most practical approach to prevent or treat a disease, as hard as it may be.

The writer is a practicing cardiologist and a current member of the advisory council for National Heart, Lung, and Blood Institute at the National Institutes of Health.

Loading Comments...

Email Print

ADVERTISEMENT