Gene doping is not science fiction. There are real challenges of such kind for the upcoming Olympics in London next year. What do we mean when we talk about ‘gene doping’? Already the word is deeply value-laden, as it implies a negative connotation and that there are grounds for banning it from competition. If we aimed at a more neutral definition, we could define ‘gene doping’ as the non-therapeutic use of genes, genetic elements, or cells that have the capacity to enhance athletic performance. Gene doping employs therefore the same techniques used for gene therapy, i.e. the delivery to a cell of a gene through a carrier (usually a modified virus), with the difference that while gene therapy has the purpose of compensating an absent or abnormally functioning gene, gene doping aims either at reinforcing the muscular system (plausible targets would be myostatin and other growth factors), or at increasing the number of red cells by boosting up erythropoietin (Epo), therefore increasing the oxygen carrying capacity of the cells of the athlete. The first document gene doping case, a product called Repoxygen was administered to supposedly oblivious track & field athletes by coach Thomas Springstein in Germany, 2008, and employed exactly these gene transfer techniques to boost up erythropoietin in the athletes.
The World Anti-Doping Association (WADA) has included gene doping techniques in the blacklist of prohibited substances since 2003, but it is only since 2008 and the Repoxygen case that gene doping has moved from the science fiction realm to reality. Foreseeing a massive use of gene doping techniques in the upcoming Olympic games in London in 2012, WADA has invested nearly 2 million $ to support research laboratories to develop methods for gene doping detection. Several are the challenges for gene doping detection. To start with, the protein produced through gene doping will not be different in sequence or structure from the endogenously produced one. In addition, anti-doping techniques aimed at identifying the “markers” of the viral vectors deployed have low probability of success, as the viral vectors may be measurable only shortly after administration, lowering therefore the probabilities of spotting gene doping. Finally, detection would often require tissue sampling, as the administration of the vector would be performed directly into the muscular target tissue, but obviously muscle biopsies are not an option for the athlete, therefore excluding this mode of detection. Alternative modes of detection called “transcriptional profiling” aimed at detecting changes in protein levels compared to the physiologically measured basal level of the athlete would require simultaneous and repeated measuring of around 1,000 proteins. WADA Director David Howman reported saying to the Telegraph in 2010 that he was pretty sure that gene doping strategies will be able to be detected, but his optimism seems overly-confident, as while WADA-accredited anti-doping laboratories, such as the Drug Control Centre unit directed by Dan Cowan in London, are putting efforts to come up with strategies to detect gene doping, at the same time other other laboratories are putting together efforts in coming up with strategies. It is a racing game, and very competitive indeed.
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