Outlaw DNA [Gene Doping in Sports]

It was a single line from a longer e-mail message. But when read into the record by prosecutors at the drug trial last year of the German track coach Thomas Springstein, it caused a sensation. "The new Repoxygen is hard to get," Springstein had written. "Please give me new instructions soon so that I can order the product before Christmas."

Until that day in the courtroom, Repoxygen was an obscure gene-therapy drug developed at a pharmaceutical lab in Oxford, England, to fight anemia. The lab shelved the product when it seemed unlikely to be profitable. Once it was mentioned in court in January 2006, however, Repoxygen vaulted to celebrity-drug status in Europe. Newspapers and Web sites ran dozens of stories about the imminent danger of the therapy. "The moment that e-mail was presented in open court," a columnist wrote in the weekend paper Scotland on Sunday, was when the "era of genetic doping . . . arrived."

Repoxygen works by worming a specialized gene into its host’s DNA. In the right circumstances, the gene directs cells to start making extra...