The concept arose from a growing recognition among anti-doping researchers that cheaters were gaming the system. Although Wada has instituted random, out-of-competition testing in addition to traditional post-event drug screens, most of these tests can only detect doping agents within a small window of time, and savvy athletes can use this to their advantage, for instance, taking drugs in microdoses that clear the system quickly without spiking levels.
The passport has a number of different modules, which cover different markers in different parts of the body. For example, the first one to be used – the blood passport – aims to identify blood dopers via markers that fluctuate when someone takes a blood transfusion or a blood-boosting drug. Concentrations of haemoglobin – the protein in red blood cells responsible for transporting oxygen around the body – provide one such marker, says Eichner. If someone who normally produces a value of around 14 suddenly spikes up to 18 or 19, this suggests doping and would flag the athlete for further testing for EPO or a blood transfusion – a common way of increasing the number of oxygen-transporting blood cells in the body and increasing performance.
Another marker the passport covers is the concentration of baby red blood cells called reticulocytes. “If you take a drug to increase red-blood-cell production, you’re going to get a spike in reticulocytes,” Eichner says. Conversely, if an athlete takes a transfusion their body suddenly has a lot a more blood than it needs, and it shuts down production of red blood cells and reticulocyte concentrations drop.
A strength of the passport is that each athlete serves as his or her own reference. “We’re using mathematical models to, in a sense, predict for each athlete what the next values should be,” says Rabin. “If the next value is in the same ballpark, we can say that’s normal. If it moves significantly up or down, then we say there’s something abnormal.” It can also spot minor changes that may alert anti-doping authorities that the athlete is worth watching.
Gene tricks
But as drug testers develop better ways to detect doping substances, there is an increasing fear that cheaters will seek ways to turn their bodies into doped-up versions of themselves via genetic manipulation. Such an approach, dubbed gene doping, would turn on specific genes that are known to enhance athletic performance.
The process is similar to gene therapy, which aims to treat diseases by inserting a healthy version of a gene into a human to replace a faulty one. This is commonly done using a vehicle, such as a virus, to deliver the desired gene to targeted cells, where it can do its work. It has had some success in treating conditions such as severe combined immunodeficiency (SCID, also called “boy-in-the-bubble syndrome”). But it is still a relatively new technology with unknown risks. For example, it produced disastrous immune responses and provoked leukaemia in some patients. And in 1999, 18-year-old Jesse Gelsinger died from a severe immune reaction he developed after receiving gene therapy.
But groups like Wada believe that it is not a case of if, but when someone turns to gene therapy in sport. Genes that promote muscle gain, such as IGF-1, are an obvious target for gene doping. “Some in the muscle field have been approached repeatedly, asking what’s new and what’s available,” says Theodore Friedmann, a gene therapy researcher at the University of California, San Diego. Genes that turn on EPO are another obvious target.
The problem with gene therapy, Friedmann says, is that once initiated, it may be difficult or impossible to turn off. This could prove fatal, for instance, if an athlete who took gene therapy to raise red blood cell production developed blood too thick for the heart to pump.
