Dr. Theodore Friedmann is the director of the gene therapy program at the UC-San Diego and is considered a leading expert in the field. He also advises the World Anti-Doping Agency.

"I'm not very excited about the possibility of people doing bad work and dangerous manipulations on humans. I've been involved on the regulatory level. The function of that committee is to make sure that gene-transfer studies in humans are done carefully and with proper approval and obey to the internationally-agreed standards.

"I spend a lot of time on the regulatory side. Abuse of gene therapy damages the field. It damages people.

"People do die in the context of gene-therapy studies. It's not a slam dunk to do what seems to be a straightforward experiment.

"A lot of things can go wrong. And they will go wrong. Do something to cure a disease and then do the same thing with healthy, young athletes,

"Will athletes use these techniques? I don't have any evidence one way or another. Others have stronger opinions. Doctors have been approached all the time by athletes and their representatives. They say that the use in sport is imminent and that we may have seen the last clean, non-genetically modified Olympics."