Testing your strength: gene doping in 2008.

THE WORLD Anti-Doping Agency (WADA), an independent organization concerned chiefly with keeping drugs out of Olympic competitions, is developing tests for a form of cheating that doesn't exist yet. The agency banned "gene doping," the alteration of genes to enhance athletic performance, in 2003. Now it wants to test for it at the 2008 Olympics in Beijing.

Banning gene doping is easy. Detecting it is another matter. Performance-enhancing drugs are detected through blood and urine tests, but genetic augmentations would be hidden away in an athlete's cells and tissues. Gene therapy often uses hollowed-out cold viruses to deliver genes to tissues and cells, so Theodore Friedman, a physician at the University of California at San Diego, is trying to devise a test that will detect the antibodies produced by the immune system as it reacts to these viruses. It's not clear how the test would distinguish between antibodies produced in response to a cold and those produced by gene therapy.

Meanwhile, other gene therapy techniques that do not use viruses are advancing. No viruses means no telltale antibodies, so Friedman is also working on a test that aims to identify a molecular signature for changes produced by the introduction of new genes. He is looking at how added genes might cause other genes to alter their behavior in measurable ways.

WADA hopes publicizing its search for such tests will deter athletes tempted to take advantage of genetic enhancements. But even if gene dopers somehow make it to the Olympics before the test is ready, the agency says they still should worry. WADA has the right to test retroactively for doping infractions up to eight years after a contest.