San Francisco
GENES may pack a tragic knockout punch for some boxers. A new study has revealed that a proportion of fighters are genetically predisposed to suffer brain damage as a result of blows to the head. Although the findings are preliminary, some medical experts say that the research could lead to genetic screening, resulting in susceptible people being banned from boxing and other contact sports鈥攁 proposition that is bound to be controversial.
Barry Jordan, a neurologist at University of California, Los Angeles, presented his findings at the World Boxing Council鈥檚 First Medical Conference on Boxing Safety, held on the Caribbean island of Aruba earlier this month. He told sports doctors that fighters born with a common variant of the gene for a protein called ApoE, known as the e4 allele鈥攚hich has already been shown to put its bearers at high risk of developing Alzheimer鈥檚 disease鈥攁re more likely to develop neurological damage in the boxing ring. Jordan鈥檚 work could explain why some boxers survive hundreds of punishing brawls without suffering any obvious damage, while others show serious neurological symptoms after only a few blows to the head.
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What has long been clear is that at least 10 per cent of boxers鈥攕ome studies claim more than half鈥攗ltimately acquire a condition known as punch-drunk syndrome, characterised by poor memory, loss of coordination and slurred speech.
Jordan had noted that Alzheimer鈥檚 patients have similar symptoms, and that traumatic head injuries are known to accelerate that disease鈥檚 progress. In fact, last year, a British researcher reported that autopsies on two boxers revealed similar brain abnormalities to those seen in Alzheimer鈥檚 patients (This Week, 20 January 1996, p 4).
So Jordan and his team decided to see whether the similarity between punch-drunk syndrome and Alzheimer鈥檚 has a genetic basis. They examined DNA samples from 27 retired and 3 active boxers for the presence of the e4 allele, and related this to an assessment of the boxers鈥� neurological health.
Nearly a third of the population carries one copy of the e4 allele while about 10 per cent carry two copies. Some studies suggest that people with two e4 genes are ten times as likely to develop Alzheimer鈥檚 as a person without the allele.
When Jordan looked at the boxers, even those without e4 genes showed some evidence of neurological injury. But the third of the men with a single e4 had more extensive damage. The most seriously impaired boxer had two copies of e4. 鈥淗is condition was noticeably more severe,鈥� says Jordan.
Exactly why the e4 allele should place people at high risk of brain injury is unclear. 鈥淚t鈥檚 important to find out, because then we might be able to do something about it,鈥� says James Nicoll of the Southern General Hospital in Glasgow, who studies the link between ApoE and recovery from head injury. One possibility is that people with the e4 allele are more likely to lay down deposits of amyloid protein, which are known to be toxic, in their brain when they are injured. ApoE is involved in the transport of lipids, which are needed to repair nerve cells. So it could also be that the version of the protein encoded by e4 is less efficient at this job.
Jordan thinks that genetic profiles may in future be a common tool used by boxing coaches and doctors. 鈥淐learly, you would watch boxers with these genes more closely and try to space out their fights,鈥� he says. 鈥淎nd, of course, you鈥檇 advise them of the risk they are taking.鈥� The same concerns could also apply to other contact sports鈥攊ncluding American football and soccer, where persistent heading of the ball might cause neurological damage.
Other experts say that the implications could be far more wide-ranging. 鈥淭his work may have historic importance,鈥� says Joe Estwanik, a doctor based in Charlotte, North Carolina, and author of the book Sports Medicine for the Combat Arts. 鈥淚t opens up a real can of worms,鈥� he says, leaving doctors in a dilemma about what to tell sportsmen and women with genetic profiles that place them at high risk of brain injury. 鈥淒o you discourage them? Ban them when they are ten years old?鈥�
Jordan and Estwanik both believe that privacy concerns would prevent any mandatory genetic testing of athletes, but others disagree. George Lundberg, editor of The Journal of the American Medical Association and a prominent critic of boxing, points out that many states in the US already require boxers to meet certain medical criteria to compete. 鈥淭hey won鈥檛 let you fight if you are half-blind,鈥� he says. 鈥淭hey can certainly pass a law that prohibits those at the highest risk of injury from being allowed in the ring.鈥�
However, all the experts consulted by 快猫短视频 agree that Jordan鈥檚 finding is preliminary and needs to be repeated independently with a larger group of boxers. Jordan adds that his group is checking to see whether the same link between injury and the e4 allele can be found in soccer and American football players.