By the time the 2012 Summer Olympics ended, over six thousand blood and urine samples were tested to keep the games clean. Despite this record-setting effort, officials already predict a mightier effort in future games when athletes are tempted by a new type of performance enhancement: gene doping.

No athlete has been caught, although no test exists yet. So far, gene therapy is still in the testing phase to treat people with inherited disorders such as muscular dystrophy. But unscrupulous athletes may risk gene manipulation hoping for superhuman results.

They may be further tempted by evidence that certain elite athletes naturally possess gene variants that give them an edge. For example, cross-country skier and seven-time Olympic medalist Eero M'ntyranta has a gene variant called EPOR which produces extra red blood cells, boosting his oxygen-carrying capacity by 25 to 50 percent.

Furthermore, scientists have also found that nearly every Olympic sprinter carries a particular form of the ACTN3 gene. Another, the I variant of the ACE gene, is associated with increased endurance and found in elite British long-distance runners.

This raises interesting questions. As gene therapy for medical conditions gains momentum, would someone given the EPOR gene variant for a blood disorder be ineligible for the Olympics?

We don't think so, because any power gene by itself won't likely improve athletic performance. A combination of genes, extraordinary dedication, and professional training are what create a world-class athlete.

That may be, but given the money and fame that comes with athletic greatness, gene doping is a near certainty.