设在波士顿的优越风险管理公司的一名常务董事史蒂夫·格兰斯和他的同事胡安·恩里克斯7月18日在英国《自然》杂志网站撰文指出，有越来越多证据表明，世界顶级运动员都或多或少携带有一些特殊的“增强表现”的基因。例如，几乎每个接受测试的奥运会男性短跑选手体内都有a-辅肌动蛋白3（ACTN3）基因的577等位基因，这种基因也存在于85%的非洲人以及50%的欧洲人和亚洲人体内，不过，其他缺乏577等位基因的数十亿人可能要重新评估自己想在奥运会上获得奖牌的“美梦”是否切实可行了。
未来的奥运会将出现三幅图景。第一幅场景是，奥运会将继续成为那些天生拥有遗传优势的运动员集中大展示的“舞台”。第二幅场景是，利用让步赛（给强者不利条件或使弱者略占优势的）——目前几个非奥运项目的运动中也采用了这种比赛，来让那些天生并不具备优势基因的运动员在赛场上获得更加公平的竞争机会。第三幅图景是，如果被证明是安全的，通过基因疗法让那些天生并不携带某些基因的运动员“升级”，但“基因掺杂”这一医学实践目前被禁止使用。
在未来的几百年内，我们可能都将生活在第一幅图景中。科学家们已经证实，20多种基因变异与运动能力有关。例如，携带有ACE基因的“I”变异的运动员，比没有携带该变异的运动员更容易在爬上8000米高峰的比赛中取得成功。尼泊尔加德满都谷地雪尔帕人中，有94%的人拥有“I”变异；而其他种族的人群中，仅仅45%到70%的人拥有该变异。这一变异会提高人的耐受力。对英国跑步运动员进行的研究发现，这种基因变异在那些耐力较好的运动员中最常见。
但是，这样的变异在人群中出现的几率比较大，因此，运动员们可能需要某些特定的基因变异才能获得精英地位。随着越来越多的个人基因组被排序，研究人员开始探究一些罕见的变异，这些变异会真正将超级运动员和世界级的运动员区分开来。例如，芬兰的越野滑雪选手、七枚奥运会奖牌得主埃罗·门蒂兰塔的红细胞生成素受体（EPOR）发生的一种基因突变让他能比正常人多产生25%的红细胞，这就让他的血液中携带着比普通人更多的氧气，因此，有助于他在运动比赛中脱颖而出。(生物谷Bioon.com)
doi:10.1038/487297a
PMC:
PMID:
Olympics: Genetically enhanced Olympics are coming
Juan Enriquez& Steve Gullans
Olympians can run faster, leap higher and lift more than 'normal' humans. Of course, such elite athletes earn their titles with an astonishing amount of hard work and support. But many also have some unearned advantages: the right genes.
There is growing evidence that world-class athletes carry a minimum set of particular 'performance-enhancing' genes. For instance, almost every male Olympic sprinter and power athlete ever tested carries the 577R allele, a variant of the gene ACTN3. About half of Eurasians and 85% of Africans carry at least one copy1 of this 'power gene'. The billion or so other people who lack the 577R allele might wish to reconsider their Olympic aspirations..
More and more genes are now being linked to athletic prowess, and future Olympic officials will have to wrestle with the implications. Are the games in fact a showcase for hardworking 'mutants'? And if Olympic rule-makers admit that the genetic landscape is uneven, should they then test every athlete and hold separate competitions for the genetically ungifted?
There are three basic scenarios for future Olympics. First, the competition could continue as a showcase of athletes born with genetic advantages. Another option would be to use handicaps — similar to those that are now used in several non-Olympic sports — to level the playing field for athletes who do not carry beneficial genes. A third option, if safe, would be to allow athletes who did not win the genetic lottery to 'upgrade' through gene therapy — a practice that is now banned as 'gene doping'.
We have been living in the first scenario for centuries. More than 200 gene variants are already associated with athleticism2. For example, carriers of the 'I' variant of the gene ACE are more likely than non-carriers to successfully climb an 8,000-metre peak3. The I variant is present in 94% of Sherpas in the Kathmandu Valley of Nepal4, but in only 45–70% of people of other ethnicities5. It is associated with increased endurance. A study of British runners found that it is most common in those who race the longest distances6.
Such variants occur frequently in the human population, and athletes probably need a subset of them to achieve elite status. As more individual genomes are sequenced, researchers will begin to detect some rare variants that differentiate truly superior champions from mere world-class athletes. Eero M?ntyranta had a mutation in the gene EPOR that caused him to produce extra red blood cells, boosting his oxygen-carrying capacity by 25–50% (ref. 7), which probably helped him to earn seven Olympic cross-country ski medals.
But how easily could scientists detect whether a variant is natural or introduced? Even 'gender-verification' testing to confirm the sex of female competitors has been problematic, given the natural biological variation among individuals8.
Olympic traditions change glacially, but eventually, what was once unthinkable becomes commonplace. Once upon a time, women were allowed to compete only in Olympic tennis, golf and croquet. Until the 1970s, paid athletes were banned from Olympic competition — now, professional basketball players compete for medals. And 'extreme sports' such as snowboarding and bicycle motocross have now become Olympics-worthy.
As officials struggle with the implications of genetic data and upgrades, we will probably see, initially, a set of draconian rules against gene modification. Will a competitor who was cured of sickle-cell anaemia by gene therapy as a child be excluded? How about someone cured of an EPOR defect through use of Eero M?ntyranta's natural variant?
Just as Oscar Pistorius, the Paralympic champion runner who was once banned from the Olympics because he uses leg prostheses, will now compete in London on the South African relay team, we expect that as genetic modification becomes more common, a gradual acceptance of safe genetic enhancements will follow. After all, we watch the games today to marvel at athletes who are 'faster, higher, stronger' — whether man or woman, amateur or professional, 'disabled' or not.
