In a Swedish study, 55 men were given testosterone injections and then given the standard drug test. Most of the men tested positive, but 17 did not.
Some Athletes’ Genes Help Outwit Doping Test:
Those 17 men can build muscles with testosterone, they respond normally to the hormone, but they are missing both copies of a gene used to convert the testosterone into a form that dissolves in urine. The result is that they may be able to take testosterone with impunity.The gene deletion is especially common in Asian men, notes Jenny Jakobsson Schulze, a molecular geneticist at the Karolinska University Hospital in Stockholm. Dr. Schulze is the first author of the testosterone study, published recently in The Journal of Clinical Endocrinology and Metabolism.
Dr. Schulze learned from an earlier study that about two-thirds of Asian men are missing both copies of the gene, as are nearly 10 percent of Caucasians. The prevalence in other groups is not known.
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The gene in question adds a chemical, glucuronide, to testosterone. That converts it from a substance that dissolves in oil into one that dissolves in water and urine.
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The men with two normal copies of the gene had T [testosterone] to E [epitestosterone] ratios that soared to 100; those with one copy of the gene had ratios that reached 50; those with no copies had almost no rise in their ratios and 40 percent of them had a ratio that never reached 4.
So the gold medal goes to the guy who’s genetically untestable? Great.
(Hat tip to Educated Guesswork.)