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PARIS (AFP) — Swiss scientists have placed a major question mark over World Anti-Doping Agency (WADA) guidelines for testing for muscle-building male steroids in urine.
The test is all but useless, for it fails to take into account a key genetic variation that hugely affects levels of testosterone found in samples, they say.
Individuals who have this variation are far less likely to breach a WADA threshold that requires closer scrutiny, they add.
The genetic variant is especially widespread among Asians but, at the other end of the scale, hardly present at all among Caucasians or Latin Americans.
In theory, it would give a drugs cheat of, say, Chinese or Japanese ancestry, a massive advantage over someone of European or Mexican ancestry, the lead scientist told AFP.
When it comes to this variant, "we are not all equal, it's clear," said Christophe Saudan, of the Swiss Laboratory for Doping Analyses at the University Centre for Legal Medicine in Epalinges.
The team focussed on a gene called UGT2B17, which controls the metabolisation of testosterone.
Previous research discovered that someone who has a tiny deletion in the code of this gene secretes only minimum levels of testerone in their urine.
In fact, experiments found that volunteers with the deletion never bust WADA's testosterone threshold.
Under WADA's guidelines, samples that have a ratio greater than four to one, in testosterone to epitestosterone -- a benchmark know as the T/E -- are viewed as suspicious.
The samples are then sent to high-powered labs, which use gas chromatography to bust them open and analyse their precise chemical signature.
Past research has also found that ethnicity counts for a lot in who gets the genetic deletion. It is present in 81 percent of Asians, 22 percent of Africans, 10 percent of Caucasians, and seven percent of Hispanics.
Saudan's team took the WADA T/E benchmark to the test by factoring in the prevalence of this deletion.
They took urine samples from 171 high-level footballers aged between 18 and 36, comprising 57 men of Black African origin, 32 of Asian origin, 32 of Hispanic origin, and 50 of white (Caucasian) origin.
The samples were measured for concentration of steroids, and tested for any traces of artificial hormone enhancers.
The team then factored in the chance that the donor, based on his ethnic background, had the coveted UGT2B17 deletion, and calculated the impact that this would have on testosterone levels.
The recalibrated figures amounted to a massive difference.
Roughly speaking, a genetic deletion meant that Asian players had a roughly 40-percent lower level of testosterone in their sample than counterparts from African, European or Hispanic heritage.
This shows WADA's one-size-fits-all T/E benchmark of 4.0 is woefully off the mark, the study says.
The real T/E benchmark, if genetic variants are taken into account, would be 5.6 for men of African origin, 5.7 for white men, and 5.8 for men of Hispanic origin, it estimates.
For men of Asian origin, the level would be far lower -- just 3.8.
Saudan said the experiment was based on a statistical prediction of the player's individual genetic profile, also called a genotype, rather than an actual blood sample that could have determined it precisely.
The point behind the research, he said, was to show that WADA's single benchmark "is not fit for purpose."
"The [universal T/E] cutoff [of 4.0] is based on a consensus, but it lacks sensitivity and lacks specifics," he said in a phone interview. "Someone with the deletion has a super advantage, which is why the cutoff isn't worth anything."
Saudan said he did not favour updated WADA benchmarks that would factor in so-called racial or ethnic genotypes, saying this method would be scientifically flawed as well as deeply controversial.
Instead, he said, it was time to have a "biological passport" that would document a top-level athlete's hormonal profile, including his individual genotype.
"It would set down the athlete's individual hormone levels, so you can say whether variations are normal or may be due to illness or doping," said Saudan.
"[Genetic] variable in a population is so wide, that you can reach a common level of sensitivity" in steroid tests," he said. "You have to go for an individualised model, there's no other choice."
The study appears in the British Journal of Sports Medicine.
The test is all but useless, for it fails to take into account a key genetic variation that hugely affects levels of testosterone found in samples, they say.
Individuals who have this variation are far less likely to breach a WADA threshold that requires closer scrutiny, they add.
The genetic variant is especially widespread among Asians but, at the other end of the scale, hardly present at all among Caucasians or Latin Americans.
In theory, it would give a drugs cheat of, say, Chinese or Japanese ancestry, a massive advantage over someone of European or Mexican ancestry, the lead scientist told AFP.
When it comes to this variant, "we are not all equal, it's clear," said Christophe Saudan, of the Swiss Laboratory for Doping Analyses at the University Centre for Legal Medicine in Epalinges.
The team focussed on a gene called UGT2B17, which controls the metabolisation of testosterone.
Previous research discovered that someone who has a tiny deletion in the code of this gene secretes only minimum levels of testerone in their urine.
In fact, experiments found that volunteers with the deletion never bust WADA's testosterone threshold.
Under WADA's guidelines, samples that have a ratio greater than four to one, in testosterone to epitestosterone -- a benchmark know as the T/E -- are viewed as suspicious.
The samples are then sent to high-powered labs, which use gas chromatography to bust them open and analyse their precise chemical signature.
Past research has also found that ethnicity counts for a lot in who gets the genetic deletion. It is present in 81 percent of Asians, 22 percent of Africans, 10 percent of Caucasians, and seven percent of Hispanics.
Saudan's team took the WADA T/E benchmark to the test by factoring in the prevalence of this deletion.
They took urine samples from 171 high-level footballers aged between 18 and 36, comprising 57 men of Black African origin, 32 of Asian origin, 32 of Hispanic origin, and 50 of white (Caucasian) origin.
The samples were measured for concentration of steroids, and tested for any traces of artificial hormone enhancers.
The team then factored in the chance that the donor, based on his ethnic background, had the coveted UGT2B17 deletion, and calculated the impact that this would have on testosterone levels.
The recalibrated figures amounted to a massive difference.
Roughly speaking, a genetic deletion meant that Asian players had a roughly 40-percent lower level of testosterone in their sample than counterparts from African, European or Hispanic heritage.
This shows WADA's one-size-fits-all T/E benchmark of 4.0 is woefully off the mark, the study says.
The real T/E benchmark, if genetic variants are taken into account, would be 5.6 for men of African origin, 5.7 for white men, and 5.8 for men of Hispanic origin, it estimates.
For men of Asian origin, the level would be far lower -- just 3.8.
Saudan said the experiment was based on a statistical prediction of the player's individual genetic profile, also called a genotype, rather than an actual blood sample that could have determined it precisely.
The point behind the research, he said, was to show that WADA's single benchmark "is not fit for purpose."
"The [universal T/E] cutoff [of 4.0] is based on a consensus, but it lacks sensitivity and lacks specifics," he said in a phone interview. "Someone with the deletion has a super advantage, which is why the cutoff isn't worth anything."
Saudan said he did not favour updated WADA benchmarks that would factor in so-called racial or ethnic genotypes, saying this method would be scientifically flawed as well as deeply controversial.
Instead, he said, it was time to have a "biological passport" that would document a top-level athlete's hormonal profile, including his individual genotype.
"It would set down the athlete's individual hormone levels, so you can say whether variations are normal or may be due to illness or doping," said Saudan.
"[Genetic] variable in a population is so wide, that you can reach a common level of sensitivity" in steroid tests," he said. "You have to go for an individualised model, there's no other choice."
The study appears in the British Journal of Sports Medicine.
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