A 2011 study showed small, frequent (and effective) doses of EPO didn’t trigger alarms. And antidoping scientists fear that athletes can use other drugs to tweak blood levels and fool the test.
Pitsiladis, whose background is in genetics, thinks the secret to a foolproof test may lie inside cellular anatomy. He spent years picking through the DNA of East African runners, looking for a source to their prowess. But he couldn’t find a genetic cause. In fact, he started to wonder if they were just doping, and that suspicion led him to search for evidence of cheating on a genetic level, specifically in RNA.
RNA attaches to DNA and executes its code, to produce proteins the body needs to grow and function. If the body has been fooled into making more blood cells, the RNA should reveal it. To check his theory, Pitsiladis had to do some doping of his own. In Scotland and Kenya, he and colleagues drew blood from runners, then had them inject EPO and checked their blood several more times over a month. He plugged that blood into a machine that looks like an oversize CD player and scans for 47,000 RNA sequences, measuring how much of each one is present in the sample.
The results showed unique fluctuations in more than 100 RNA sequences in the doped blood. Pitsiladis likens it to a dimmer switch. Hit with a dose of EPO, the body responds by turning up or down the expression of certain genes. Some fragments of RNA were 16 times more plentiful in the doped blood. He could still find this fingerprint four weeks after the injection. “Most exciting data of my career,” Pitsiladis said.
Catching someone doping with their own blood can be trickier. But in Umea, Sweden, 250 miles south of the Arctic Circle, Christer Malm thinks he might have found a way. He extracted blood from 11 people, froze it for 15 weeks and then reinjected it. When comparing these samples to normal blood, Malm could always pick the doped blood out of a lineup by looking for unusual amounts of certain proteins. He suspects the changes are caused by the body’s reaction to the new blood, combined with a sort of freezer burn that develops as the blood ages.
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