Genes and Drug Testing

Thursday, August 07, 2014. Author Mark Gilbert

 Genes and Drug Testing

What if we told you that a significant number of people have a certain gene type (a version of an ‘insertion/deletion’ genotype) that would allow them to beat a drug test? Well, it’s true! Research published in the Journal of Clinical Endocrinology and Metabolism has demonstrated that from 4–60% (depending upon genetic heritage; whites: 4%, Koreans: 60%) of athletes have a gene type that results in different amounts of steroid metabolites being excreted in their urine.

You see, the primary anti-doping test for use of testosterone in sports is the measurement of the testosterone to epitestosterone (T:E) ratio and this is done by measuring two metabolites produced by the body, called testosterone glucuronide and epitestosterone glucuronide. If the ratio of these exceeds 4:1, then that athlete’s sample goes for further testing to confirm the use of testosterone and if it tests positive that athlete gets disqualified and banned. However, if their sample doesn’t exceed this ratio, the athlete is assumed to be ‘clean’ and not to have used ‘test’. The problem is, depending upon the version of an athlete’s gene called uridine diphospho-glucuronosyl transferase 2B17, they might produce up to 20 times more or less testosterone glucuronide than another athlete who has used the same drug. So if two athletes who take the same large dosage of testosterone are tested, one could sail through the testing unscathed and the other could find himself returning his gold medal and being banned from his sport… all because of their version of one gene!

That’s right, according to this research, over 50% of athletes from some countries wouldn’t test positive for using an anabolic steroid. Specifically, careful laboratory testing has shown that these individuals can take 500 mg of testosterone enanthate (a proven performance enhancer and five times the usual therapeutic dosage) without testing positive for doping under present IOC testing methods. Not only does this mean that some athletes who doped at the last several Olympics are almost certainly walking around with ill-gotten medals, it also means that right now in some (many?) countries, athletes are probably being chosen at least in part because they can take performance-enhancing drugs and stay under the test’s radar!

At FitnessGenes™, we don’t test for uridine diphospho-glucuronosyl transferase 2B17 because we focus our testing on genes that allow us to make effective recommendations on how to improve body composition and performance for your personal gene types (and this gene isn’t such a candidate). However, we do test the ACTN3 gene, which affects testosterone levels and signalling and (partly due to this) affects recovery from exercise.

Best wishes



Jenny Jakobsson Schulze, Jonas Lundmark, Mats Garle, Ilona Skilving, Lena Ekström and Anders Rane Doping Test Results Dependent on Genotype of Uridine Diphospho-Glucuronosyl Transferase 2B17, the Major Enzyme for Testosterone Glucuronidation. The Journal of Clinical Endocrinology & Metabolism Vol. 93, No. 7 2500-2506

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