The completion of the Human Genome Project (HGP) in the early 2000’s and advances in gene therapy over the past two decades have raised some ethical concerns due to the interest of some athletes to use this technology as a method to enhance their performance in sports (Brzeziańska et al. 2014). At the time of its inception the goal of gene therapy was to introduce a functional copy of a gene into a person to treat or prevent certain genetic diseases. There are two approaches used to deliver a gene to target cells: in vivo and ex vivo. In the in vivo approach, the gene is typically packaged into a viral or non-viral vector and directly injected into the patient; On the other hand, in the ex vivo approach cells are first collected from the patient, genetically modified, cultured, selected for and reintroduced into the patient’s body (Moss 2014). In both cases, the expectation is that the target cell’s machinery will regulate the expression of the newly introduced gene and a functional protein will be produced as well. Although there have been a few examples of successful gene therapy trials in humans such as the treatment of ADA-SCID in children (Herzog et al. 2010) there have been other reported cases where the therapy resulted in the death of the patient due to strong inflammatory reactions (Gould 2012). The approved clinical trials in humans highlight that although there is great potential in using gene therapy to treat genetic diseases that do not have any other form of treatment, there is still much to be learned about the risk factors involved.
As gene therapies for the treatment of anemia, muscular dystrophy and certain vascular diseases have been identified and successfully tested on mice, the concern for their potential use by athletes to gain an edge in their sport has prompted action by various sporting organizations (Unal 2004). An example of a gene that could potentially be used for gene doping came from the work of Lee and colleagues (2004) where the injection of the gene encoding the insulin-like growth factor-1 (Igf1) into rats displaying muscular dystrophy resulted in an increase in muscle mass and strength, which could be beneficial for endurance sports. Another study performed by Wang et al. (2004) where the PPARδ gene was injected into skeletal muscle of some rats resulted in their ability to run twice the distance in comparison to rats not receiving the gene therapy. This results suggested its potential to aid athletes involved in sports requiring endurance and long distances. Although this are only two examples of genes that could potentially be used in doping, other candidate genes recently studied include EPO, VEGFA, HIF-1 PCK-1 and rEPO for endurance sports and MSTN, GH, and rhGH to enhance athletes in strength sports (Brzeziańska et al. 2014).
References
- Brzeziańska, E., Domańska, D. Jegier, A. (2014). Gene doping in sport-perspectives and risks. Biol. Sport. 31: 251-259.
- Gould, D. (2012). Gene doping: gene delivery for Olympic victory. British Journal of Clinical Pharmacology. 76 (2): 292-298.
- Herzog, R. W., Cao, O., Srivastava, A. (2010). Two decades of clinical gene therapy- success is finally mounting. Discovery Medicine. 9 (45): 105-111.
- Lee, S., Barton, E. R., Sweeney, H. L., Farrar, R. P. (2004). Viral expression of insulin-like growth factor-I enhances muscle hypertrophy in resistance-trained rats. Journal of Applied Physiology. 96: 1097-1104.
- Moss, J. A. (2014). Gene therapy review. Radiologic technology. 88 (2): 155-180.
- Pray, L. (2008). Sports, gene doping, and WADA. Nature Education. 1 (1): 77.
- Unal, M., Unal, D. O. (2004). Gene doping in sports. Sports Medicine 34 (6): 357-362.
- Wang, Y. X., Zhang, C. L., Yu, R.T., Cho, H. K., Nelson, M. C., Bayuga-Ocampo,C. R., Ham, J., Kang, H., Evan, R. M. (2004). Regulation of muscle fiber type and running endurance by PPARdelta. PLoS Biology. 294 (2): 1532-1539.
