Saturday, March 29, 2014

Is There Really a Sports Gene? - Medscape

David Epstein
March 21, 2014
Editor's Note:

At the Future of Genomic Medicine VII conference in March 2014, leading experts in genomic research and clinical application discussed the expanding influence of genomics on the practice of medicine. Medscape asked David Epstein, author of The Sports Gene: Inside the Science of Extraordinary Athletic Performance, to offer some insight on what clinicians need to know about advances in sports and exercise genetics.
Medscape: Are there individuals with a genetic predisposition to excel in sports?
Mr. Epstein: It is a complicated question and, to some degree, is dependent on the sport skill you are talking about. Some things that were previously thought to be genetic characteristics, such as the bullet-fast reactions of Major League Baseball hitters, turned out to be really the result of practice, whereas other things, such as the compulsive drive to train, turn out to have important genetic components. So it really depends on what you are looking at.
Part of what is coming out of sports and exercise genetics is an idea similar to what came out of medical genetics. Medical genetics is showing us that in some cases, no 2 people will respond to, say, acetaminophen the same way because of differences in genes involved in acetaminophen metabolism. Exercise genetics is showing that this is the same for the medicine of athletic training. No 2 people, because of their genes, will respond quite the same way to the same training stimulus. The goal is to find the optimal training and exercise environment, whether it is for a sports performance or for health effects, for each person's individual genome.
Medscape: How should clinicians address these issues in their own practices?
Mr. Epstein: There are a couple of things that clinicians should keep in mind. Some of them now get questions about testing for genes for athleticism, and usually this will include a gene such as the ACTN3gene, which codes for protein found only in fast-twitch muscle fibers. It is sort of sexy to test for this gene now. If you don't have one of the so-called right versions for sprinting, you just won't be in the Olympic 100-meter final. But that only rules out 1 of 7 billion people on earth, so it is incredibly nonspecific.
To make a decision for a child about what sport they should pursue on the basis of this one gene is like looking at one piece of a puzzle that has a thousand pieces and deciding what the puzzle shows. It is incredibly complex. We don't know a lot of the genes, much less the environmental stimuli that go into this.
For the most part, I think genetic testing for sports prowess should just be ignored. You are better off just seeing what the kid is good at physiologically. The best genetic tool you have for sprinting right now is a stopwatch, not the ACTN3 gene.
That being said, I do think there are genes that clinicians should consider talking with patients and parent about -- genes that predispose people to injuries, such as torn tendons and ligaments. These are genes that code for collagen. And I think it is time to have the conversation about the so-calledAPOE-4 gene variant. We have known for a long time that it predisposes people to having Alzheimer disease, but it now looks like it is involved in all manner of recovery from brain injury.
We are having this national furor about brain trauma in football and, to a lesser degree, in soccer, and there is this gene variant out there that might give some risk information.
When I have talked to clinicians, generally their take has been, "No, we don't want to test people for this, because it is just statistical risk information." But telling someone that smoking puts them at an increased risk for heart attack is also just statistical risk information. And the response I get to that is, "Well, they can stop smoking, but they can't change their DNA."
True -- but they absolutely can change their environment by, for example, not playing football. I think that is a discussion that clinicians should be having with patients soon.
Medscape: Where is research in this field headed?
Mr. Epstein: I think the direction that sports and exercise genetics are going toward is individualized training, to a degree. Obviously, it is very difficult, and we have seen some of the difficulties of individualized medicine. But scientists are making some strides in finding genetic markers that predict differences between people and their responsiveness to a particular training plan. Whether that is how much their cardiovascular system strengthens or how much their blood pressure drops, the idea would be to be able to tell someone, "Look, you want this drop in blood pressure, and you have a set of genes predicting that you can get that with this training, or without even training that hard" -- whereas with some other person, you say, "Wow, you would have to train really hard, so you may need to be medicated." We are making strides in that direction.

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