Could a politician's DNA be abused in a campaign?

— -- In this year's presidential race, John McCain's campaign made sure voters heard about his mother, still sharp and energetic at 95, while Barack Obama's campaign staff kept relatively quiet about his grandfather's death from prostate cancer, a history that suggests an above-average risk of prostate cancer.

Family history is one thing, but what if voters had access to detailed genetic information about the candidates themselves? Could candidates be doomed politically if the electorate learned they carried genes that raised their risk of lethal diseases or psychiatric conditions?

That idea might not be so far-fetched, scientists suggest today in the New England Journal of Medicine.

Although only a handful of humans have had their entire genome sequenced so far, the price of doing so is dropping, and DNA is pretty easy to obtain, especially from someone who shakes a lot of hands and eats a lot of rubber chicken, says lead author Robert Green, a professor of neurology, genetics and epidemiology at Boston University.

Last month, Complete Genomics, in Mountain View, Calif., announced it plans to sequence 1,000 humans' genomes in 2009 for $5,000 each — about 1/20th the current cost. And enough DNA to sequence can be obtained from "coffee cups, discarded utensils, or even a handshake," say Green and coauthor George Annas, a Boston University bioethicist.

"There are some legitimate things you can learn," Green says, such as whether an older candidate has a higher-than-average risk of Alzheimer's disease. But, he says, a 20% higher risk of breast or prostate cancer or diabetes isn't very informative when the average risk is fairly low to begin with.

"People can be fooled by numbers and how numbers can be spun," Green says. "We are heading into an era where there's going to be more and more information, and, for a little while, it's going to be more difficult to interpret." For the "foreseeable future," he and Annas write, genome sequencing "is likely to result in large numbers of false positive findings."