Gene therapy vs. gene doping

To achieve the aims of athletes the start of the circulatory and breathing systems as well as the adaptive mechanism of skeletal muscle are needed. Their effectiveness is genetically determined.  This study has already pointed out that physical qualities are determined by specific gene variants, for example, speed, endurance, muscles and emotions.

The development of molecular medicine has made possible to use methods analysing genes. By applying the methods and techniques of molecular biology (for example, in situ hybridisation, DNS chip technique, polymerase chain reaction analysis) the change of only one singular nucleotide in the DNS genomic sequence can also be identified.

These methods can modify humans’ genetic stock to be able to treat diseases. Often it means the injection of one single functioning gene copy into cells. Other gene therapy strategies use the method of suppressing with little interfering RNS (siRNS) or antisense oligon-nucleotide. In 2012 Glybera was accepted as the second gene therapeutic agent in the EU. The normal variant of lipoprotein lipase - one of the enzymes participating in lipid metabolism- is used in lipase deficiency (LPLD). In America in January 2013 Kynmaro, injection was approved and introduced as a gene expression lowering siRNS gene therapy drug for the treatment of homozygous familial hyper-cholesterolemia. Nowadays a lot of work is done to create a new more efficient gene technology. Is should not be denied that peak technologies may support illegal therapies which enhance athletes’ performance.

In the course of gene doping exogene genetic sequence is injected into different tissues with the aim of changing gene activity or inducing protein production. Most exogenes applied in gene doping encode peptide hormones, for example, erythropoietin (EPO), growth hormone (GH), vascular endothelial growth factor (VEGF-A, VEGF-D), insulin-like growth factor-1 (IGF-1) and myostatin antagonist follistatin (FST). These proteins can be found on the blacklist of WADA, World Anti Doping Agency (http://www.wada-ama.org). By using these gene therapies successfully means that our body increases the production of these proteins affecting performance and/or muscle power. Gene expression lowering techniques (siRNS, antisense nucleotides) can be used to lower/reduce the myostatin gene expression as a means of blocking muscle growth.

At the beginning of 2003 the International Olympic Committee and WADA blacklisted gene doping. Gene doping is defined as the non-therapeutic use of cells, genes, genetic elements, or the modulation of gene expression which increase physical performance. According to WADA each drug and stem cells transplantation is forbidden that enhances sports performance. By this the followings are meant: nucleic acids, the transfer of polymers of nucleic acid analogues and the genetically modified sells. If athletes undergo an in vivo gene transfer in blood, locally into tissues, skin, muscle, or they get genetically modified cells ex vivo they are automatically disqualified.

Between 2004-2007 the WADA project 21 coordinated genomics, transcriptomics, proteomics, metabolomics, virology and bioinformatics. This strategy has helped identify and detect those genes and their variants which may have affected athletes. Gene doping has two possible methods. The classical one is to inject/administer synthetic DNS sequence with viruses into a body; the other option is to use RNS interference strategy. Between 2010 and 2011 WADA coordinated two gene doping detection methods. The aim was to identify erithropoietin (EPO), insulin-like growth factor 1 (IGF-1), vascular endothelial growth factor (VEGF-A, VEGF-D), human growth hormone (hGH), follistatin (FST) and genes encoding regulatory transcriptional factors.

The diversity of individuals’ gene by affecting the metabolism of performance enhances substances that may inhibit the detection of the prohibited materials and drugs. The UDP-glucuronosyl-transferase 2B17 (UGT2B17) enzyme catalyses the transfer of the testosterones of glucuronids and steroid becomes water soluble. To detect testosterone doping the ratio between testosterone, or its epimre, the epitestosterone (TE) in urine is examined and tested. The average rate of T/E is about 1. According to WADA further doping tests are needed if the ratio is 4:1. The gene variants of UGT2B17 may inhibit the abuse of testosterone detection. Individuals’ testosterone is excreted in small amount of glucuronide from the urine. These people have del/del genotypes. Their T/E ratio is only 0.14. In case of ins/del (it has one UGT2B17 copy) this ratio is 1.4, whereas it is 2.9 when the genotype contains 2 copies. The UGT2B17 gene polimorhysms prove the impact on the excretion of testosterone from urine. This was confirmed by the fact that males were injected testosterone-enanthate and the T/E ratio in the urine was followed up. The del/del genotype males’ test based on T/E ratio showed significantly lower sensitivity than that of the ins/del or ins/ins individuals. In the African and European populations the deletion of UGT2B17 variant is rarer in contrast to Easter-Asian peoples who could have the advantage of this possibility regarding the abuse of steroids.