The Russian Federation isn’t at the 2020 Tokyo Olympics. Its athletes aren’t wearing its signature stripes of white, blue, and red, nor are they carrying its flag. In 2017, the International Olympic Committee banned Russia from competing in the Olympics. Their charge? Doping.
After an independent investigation led by the World Anti-Doping Agency (WADA), investigators found that Russian officials were doping the country's athletes, providing them with performance-enhancing drugs that supercharged their elite athletic abilities. The investigation caused a massive public outcry around the world and took down a number of athletes who were instrumental to the nation’s success at the 2014 Winter Olympics at Sochi.
But what if they hadn’t used performance-enhancing drugs? What if athletes could turn to more internal changes to amplify their athleticism?
That is the promise – and peril – of gene editing. Genome editing allows scientists to alter the DNA in an organism, whether through adding, subtracting, or changing the genetic code at a specific location. There are many methods for editing DNA, but the most commonly mentioned are CRISPR-Cas9 and TALENs, and the implications for not just the Olympics but all sports deserve serious consideration.
Gene editing methods
Two of the inventors of the CRISPR technique, Jennifer Doudna and Emmanuelle Charpentier, won the Nobel Prize in Chemistry for its development. CRISPRs, or Clustered Regularly Interspaced Short Palindromic Repeats, are repeated sequences of DNA interspersed with unique sequences of spacers. CRISPRs are naturally occurring— they’re used by bacteria and archaea to fight off pathogens by slicing up the intruder’s genetic material and adding these slices to its own genome as a sort of "library". Since the pathogens’ genes become a part of the bacterium’s genes, the bacteria can “remember” the pathogen and better fight it in the future.
How did we turn this microbial defense into a gene-editing powerhouse? It all starts with RNA. The spacer sequences from CRISPR can be transferred into RNA sequences – the A, C, G, and U. The RNA acts as a guide, bringing the CRISPR system to a specific spot on the DNA. The Cas9 enzyme (or other enzymes) are used to bind to this DNA location and gives it a snip, sending off alarm signals within the cell. The cell desperately tries to fix the cut DNA, and in doing so pastes the ends back together, this time without the gene or genes cut off by the enzyme. The result? Scientists can activate or delete parts of the genes or sequences of DNA that change some function of the organism.
TALENs, or Transcription Activator-Like Effector Nucleases, is another method being used for efficient gene editing. Xanthomonas genus bacteria wreak havoc on plants, injecting a protein called TAL that can shut down a plant's genes. This protein might be bad for plants, but for scientists, it’s opened up the world of gene editing even more. TAL is made up of sections that can identify certain DNA nucleotides, and tinkering with these sections allows scientists to locate genes they want to edit. When TAL is matched up with endonuclease, which bacteria use to destroy pathogenic DNA, it creates the TALEN system— TAL protein and ENdonuclease.
Biology and athleticism
During the Olympics, the physiological prowess of elite athletes is clear, whether it’s the long-limbed volleyball players or the muscular weightlifters. Unsurprisingly, physiological advantages vary by sport, but there’s a number of genetic advantages that can arise.
Lance Armstrong was considered to be one of the most talented cyclists in history before his infamous doping scandal. Even without performance-enhancing drugs, Armstrong still had a genetically powerful build for cycling: he has a higher maximum oxygen consumption than the average person. Maximum oxygen consumption, or VO2max, was thought to be based solely on exercise, but the trainability of VO2max, and VO2max more broadly, are increasingly associated with genetics.
Michael Phelps, the most decorated Olympian of all time, naturally produces half the lactic acid of other Olympic swimmers. When we perform high-energy activities, the body switches from generating energy aerobically (with oxygen) to generating energy anaerobically (without oxygen). During this process, the body breaks down a substance called pyruvate into lactic acid. This lactic acid tires out muscles, leaving them with that all-too-familiar burning sensation when you exercise. Since Phelps doesn’t have as much lactic acid, he’s able to recover from high-intensity activity quickly.
In recent years, there’s been major controversy surrounding testosterone and female athletes.
Just recently, Namibian Olympian Christine Mboma was barred from competing in the 400m race on the basis that her testosterone levels were too high. It’s worth noting that testosterone, while it does play a role, may not be the most crucial element in athletic performance.
Many studies linking an association between the hormone and athleticism are inherently flawed, as they test the impacts of exogenous testosterone— in essence, they test the effects of doping rather than naturally occurring testosterone. Roughly 1 in 4 male Olympians have testosterone levels that are lower than that present in most men, and many of these athletes were competing in sports such as weightlifting and track, which are often associated with testosterone.
Genetically modifying athletes
Here’s the question: could we create designer elite athletes using genome editing? It’s complicated.
In 2018, news broke that twin girls in China were genetically modified using CRISPR to be born immune to HIV. Conducted by He Jiankui, the experiment supposedly neutralized the CCR5 gene, which enables HIV to infect an individual. He Jiankui was subsequently sentenced to three years in prison.
However, the ethics behind genome editing in humans are hotly contested. The US National Academy of Sciences and National Academy of Medicine have hosted an interdisciplinary committee to outline the regulatory standards and ethics of human gene modification. The very first of these regulations was that genome editing can occur if it is restricted to preventing the transmission of a serious disease or condition.
The World Anti-Doping Agency recently placed gene editing on their list of prohibited practices and substances. There’s just one problem— it’s extremely difficult to determine if someone has modified their genome. One study, however, has shown promise in alleviating this issue by detecting leftover inactive Cas9 from the CRISPR-Cas9 editing process. However, if an enzyme other than Cas9 or a different method altogether (like TALEN) is used to edit the gene, then this method cannot be used.
In theory, we could genetically engineer children to grow into “better” athletes: a runner with stronger leg muscles, a taller volleyball or basketball player, an archer with pinpoint vision. But before we go full-on Gattaca, it’s worth considering that if every athlete is identical, has the same strength and flexibility, then what happens to the excitement of the game?
What happens to watching, eyes glued to the screen, as the underdog beats the time-honored pro? Or enjoying the suspense of the world champion team going up against a lower-seeded rival with something to prove? Genome editing might not have a role in sports yet, but it begs the question: if genome editing makes an appearance in sport, would the joy of the games disappear?