American cyclist Tyler Hamilton effectively lost his livelihood last month following a two year suspension handed down from an arbitration panel's 2-1 finding (found through Fat Kid, where he and I futilely went round and round on whether Lance Armstrong was/is a doper) that he was guilty of blood-doping; his sample contained evidence of another person's blood. He is the first athlete banned using this novel test, and has vowed to appeal.
After reading the panel's findings (I found the dissent pretty weak), and knowing how the World Anti-Doping Agency has sworn to crack down on cheaters, I was initially skeptical about his chances, but after reading this IHT article
, it seems that the test may be unreliable.
The problem lies with the rate of false positives. The arbitration panel agreed with the scientific evidence provided them that showed an almost negligible rate of false positives. The article notes that several experts are offering contrary opinions.
On the other hand
...[Tyler] offered a surprising defense: The small amount of different blood found mixed in with his own must have come from a "vanishing twin."
In other words, his scientific expert argued, Hamilton had a twin that died in utero but, before dying, contributed some blood cells to him during fetal life. And those cells remained in his body, producing blood that matched the dead twin and not Hamilton. Or perhaps it was his mother's blood that got mixed in during fetal life.[...]
Dr. Ann Reed, chairwoman of rheumatology research at the Mayo Clinic, who uses sensitive DNA tests to look for chimerism, finds that about 50 percent to 70 percent of healthy people are chimeras. The more scientists look for chimerism, the more they find it. It seemed not to exist in the past, she said, because no one was looking for small amounts of foreign cells in people's bodies.[...]
The Hamilton case involves a test developed by Dr. Margaret Nelson and her colleagues at the Royal Prince Alfred Hospital in Australia. It was based on a simple idea: If an athlete got a transfusion, he would have to make sure the blood was the right match using the blood antigens A, B and O. But blood cells have other surface proteins, so-called minor antigens, that do not matter in blood typing for transfusions but can be used to distinguish one person's blood from another's. The investigators said they could use a sensitive test, flow cytometry, to search for small amounts of blood with minor antigens different from those in the athlete's own blood.
It was an important advance, anti-doping agency officials said. They knew that athletes, including cyclists, had used blood transfusions in the past to boost their performance but had no test to prove it.
But there is evidence that that test may be difficult to perform. The qualifications of the technicians who performed the test are sure to be part of the appeal.
Brown, the only outside scientist that the anti-doping agency suggested to present its point of view, said blood banks almost never found chimeras. The blood banks used a less sensitive test, but Brown testified that he himself, using the more sensitive flow cytometry on at least 20,000 blood samples, never found a chimera. And, he said, reports of people with small amounts of foreign cells do not signify that an athlete with a second population of blood cells had someone else's blood stem cells in his bone marrow. Moreover, he said, Hamilton tested negative a few months after his positive test last fall. That is consistent with an athlete who had transfusions, was caught and then stopped.
Troubling stuff for one who hates cheats, especially cycling cheats. To my mind, however, the level of chimerism is likely to be dispositive in this and other cases. What I mean is that even if chimerism in the general population is more prevalent than previously believed, if Hamilton had a high percentage of chimeric blood cells floating around--rather than the few the article seems to be discussing--the judgment will likely be upheld.
Not only was a vanishing twin or chimerism a real possibility, [Dr.] Housman [Prof. of molecular biology at MIT] decided, but he had real questions about whether the test was reliable enough to use to look for blood doping.
Dr. Gerald Sandler, a professor of medicine and pathology at Georgetown University Hospital, who previously was medical director for the national reference laboratory for blood group serology at the National Red Cross and who has no involvement in the Hamilton case, said the test was acceptable for research. But, he said, its results could easily differ from lab to lab. It "is being misapplied," he said, when it is used to accuse athletes of blood doping.
Dr. V.K. Gadi, a hematologic oncologist at the Fred Hutchinson Cancer Center in Seattle who uses flow cytometry in his research, says that "the test can be quite finicky from experiment to experiment."[....]
I hope both sides present their best cases and that the appeals process is fair (not always a guarantee with international bodies that too often see the ends as justifying the means). However, given the circumstantial evidence surrounding Hamilton's case (gleaned from the arbitration desicion), I still come down on the guilty side.