There is a growing feeling that genetic testing will offer major changes in medicine, and that both diagnosis and drugs will be tailor made to each of us based on detailed analysis of our DNA some time in the next few years.
While appealing, this unfortunately is an extremely unlikely scenario. It turns out that only a few, relatively rare, diseases are due to changes in single gene function. Probably the most common is sickle cell anemia, and there are a handful of others. There are, for instance, a very small number of women who are at very high risk for early breast cancer due to a genetic mutation, but the overwhelming majority of breast cancers don't fall under this category.
The same is true of colon cancer, where a very small number of families carry a gene that predisposes them to a very high rate of colon cancer, but again this is a drop in the bucket compared to the overall numbers of colon cancer in our country.
It is appearing more and more as if the vast majority of common diseases are what is called "polygenic", meaning that many genes interact to raise or lower your susceptibility to the specific disease. It is going to be years and years before these interactions are all understood, and when they are, it is highly likely that the biology will be complex enough that treatment will be just as difficult as it is now.
On the other hand, the good news is that life style does influence your susceptibility no matter what your genetics, so it is worth taking a very detailed family history, going back as many generations as you can, and going out to first cousins, aunts and uncles. If any patterns emerge, take them seriously as risks, not so much in terms of testing strategies, though you can discuss this with your doctor - but in terms of changing around your life style, especially nutrition, exercise, and emotional connections, to lower your risk of things like heart disease, cancer, Alzheimer's, and diabetes.
Knowing that you are at genetic risk for illness changes the lifestyle equation from something you ought to be doing, to something you simply have to do, with no options, and that makes it much, much easier to get to the gym in the morning, or reach for an apple instead of a doughnut.
Published On: July 19, 2007