That is exactly what worries officials at the World Anti-Doping Agency and the U.S. Anti-Doping Agency. In anticipation of the 2004 summer Olympics, in Athens, the world agency put gene doping on the International Olympic Committee’s prohibited list, which includes everything from cough syrup to cocaine. The prohibition defines gene doping as “the nontherapeutic use of genes, genetic elements, and/or cells that have the capacity to enhance athletic performance.” But no one thinks for a minute that gene doping isn’t already starting to happen. “Sport is supposed to be fun,” says former Olympic swimmer Richard Pound, ex-president of the world agency and a vocal champion of the antidoping cause. “But it is surrounded by people who are conspiring to destroy the athlete and the game.”
Gene doping is different from chemical performance-enhancing techniques. Human growth hormone, for example, occurs naturally in the body and will accelerate cell division in many types of tissue. Taken in high doses, it can provide a head-to-toe muscle boost and can even add a few extra inches of height. Anabolic steroids are chemical relatives of testosterone. They are believed to be in wide use in professional sports—although most athletes deny it—and their illegal use recently ignited explosive, high-profile controversy in Major League Baseball and Olympic track-and-field events. Last year track star Marion Jones admitted that she had used steroids while training for the 2000 Olympics and was stripped of all five of her medals. Steroids are also popular with weight lifters because they foster new muscle growth in the upper body. Synthetic erythropoietin, or EPO, a chemical naturally produced by the kidneys, is a favorite of triathletes, marathon runners, Tour de France cyclists, and others who engage in long periods of aerobic activity. EPO flushes fatigued muscles with oxygen to stave off exhaustion.
These and other substances can be detected in blood and urine tests because they drift through the circulatory system for hours, days, or months. Gene doping is not so easy to spot. Genetic modifications become an indistinguishable element of the DNA in targeted muscles. The only way to prove that someone has used gene doping is to biopsy a suspicious muscle and look for signs of DNA tampering. It is not hard to imagine that most athletes will object to having bits of flesh sliced from the very muscles they’ve spent years honing. “Athletes aren’t going to say, ‘Hey, take a muscle biopsy before my 100-meter run,’” comments Johnny Huard, who developed his own set of muscle-building genes as professor of molecular genetics, biochemistry, and bioengineering at the University of Pittsburgh School of Medicine.
Lack of easy detection makes gene doping extremely attractive to athletes. But the incredible muscle-building power of doping is the big draw. Sweeney believes gene-doped athletes would readily surpass their personal bests and could even smash world records. Sprinters and weight lifters would see the most benefit, their peak speeds and maximum strength amplified. “Athletes would be able to push their muscles harder than ever before because their muscles would repair themselves so much faster,” he says. “And they wouldn’t have to retire when they were 32.”
Antidoping agency officials are convinced that athletes will try gene doping, despite its dangers. “In the current climate there is even more pressure than when I was competing,” says Norway’s 1994 Olympic speed skating gold medalist, Johann Koss, a physician and former member of the World Anti-Doping Agency’s executive board. “People will take shortcuts. Being the best in the world offers huge financial gains.”
In a poll, American athletes said they would take any drug that would help them win, even if they knew the drug would eventually kill them.
Pound cites a poll of American athletes who said they would take any drug that would help them win, even if they knew the drug would eventually kill them. “Nobody ever said athletes are ?the smartest people in the world,” he comments. “This is why there has to be paternalism. This is why I don’t let my kids drive the car at age 13, even though they tell me they can do it safely.”
Pound has good reason to worry. The newest gene therapies work on mice, rats, and dogs with no apparent adverse effects. Until clinical trials are completed, however, it is impossible to know exactly what the effects will be on humans. Sweeney acknowledges, for instance, that IGF-1 could make precancerous cells grow faster and stronger.
“We have absolutely no clue” about side effects, Huard says, but he and other researchers are worried about immunologic reactions to the virus that serves as the gene carrier. That reaction is apparently what killed 18-year-old Jesse Gelsinger, according to researchers at the University of Pennsylvania. Gelsinger had a rare liver disease and was participating in gene therapy research at the university when he died. The Food and Drug Administration immediately terminated all gene therapy trials there, and the incident prompted federal regulators to establish new rules for human gene therapy research.
More and more, Sweeney says, the immune system is proving to be the most difficult hurdle in developing gene therapy for humans. Treatments that appear perfectly safe in rodents and dogs can provoke a devastating immune response when adapted for humans and other primates. The problem, Sweeney says, is that the viruses researchers use for delivering therapeutic genes infect primates but not other mammals. So while a dog’s immune system will simply overlook the intruder, a human’s will recognize it and launch a massive attack. Researchers are now working to develop ways to suppress the immune system long enough for the virus to safely deliver its genetic cargo.
