The genetic variations can be used to identify susceptibility to a particular disease and to pinpoint targets for drug treatments.
Currently drug courses are often ineffective. Physicians may have to prescribe several different treatments before identifying one that works.
"Personalized medicine is about changing the medical paradigm," said Edward Abrahams, executive director of the Personalized Medicine Coalition in Washington, D.C. "It promises to replace trial-and-error medicine with a more targeted get-it-right-the-first-time approach."
Many cancer patients can already use targeted drugs such as Novartis's Gleevec and Genentech's Tarceva that are known to work better in people with certain genetic profiles.
And a study published recently in the Journal of the American Medical Association showed that variations in one particular gene can predict which patients will respond to antidepressant drugs such as Eli Lilly's Prozac.
No Easy Feat
But personalized medicine still faces huge obstacles. Genetic testing, for instance, is hugely expensive right now. It currently costs millions of dollars to sequence one complete human genome.
Scientists are optimistic, however, that in as little as five years the cost could be less than a thousand U.S. dollars.
The Santa Monica, California-based X Prize Foundation recently announced a ten-million-dollar reward to the first company that can process the genetic codes of a hundred people in just ten days. (Related: "SpaceShipOne Wins Ten-Million-Dollar X Prize" [October 4, 2004].)
And the National Human Genome Research Institute has announced grant awards of more than U.S. $13 million to speed the development of innovative sequencing technologies that reduce the cost of DNA sequencing.
"The science is there, but the technology needs to come into place that brings the cost down," Abrahams, of the Personalized Medicine Coalition, said.
Collins, of the NIH, says that there are still ways to apply individualized medicine even without having a person's entire genome sequence.
Researchers can focus on specific places in the genome where they know there are genetic variations between people that carry a particular risk for disease, he says.
"You would do what's called genotyping," he said, "assessing spelling in a particular place on a chromosome where you know something important resides. We can already do any genotype on a particular DNA sequence for pennies or less."
Perhaps a more significant obstacle, Collins says, is to educate both physicians and patients about the use of sophisticated genetic tests.
Personalized medicine doesn't mean that "doctors are going to say, OK, you have this DNA 'spelling' so you're going to get cancer of the colon on your 43rd birthday," he said.
"Instead, the [genetic variations] are going to be statistical risk predictors. But these can be extremely useful in allowing people to practice their own more individualized preventive medicine.
But many people have strong concerns about how genetic information should be used.
If genetic testing reveals a patient's predisposition to a certain condition, insurance companies could, for example, use that information to deny the patient health coverage.
A legislative bill prohibiting the use of genetic information in insurance and employment decisions has already passed the U.S. Senate but remains stuck in the House of Representatives.
What's more, a recent survey conducted by Research!America, a medical research advocacy group based in Alexandria, Virginia, showed that only one-third of Americans have heard the term "personalized medicine."
Once the term was defined for them, more than 80 percent of respondents said they believe increased availability of personalized medicine will improve doctors' abilities to diagnose diseases and evaluate a patient's risk for disease.
"People are positive about the concepts of personalized medicine to the extent they've heard about it," said Mary Woolley, Research!America's president.
Survey results showed that almost seven out of every ten U.S. residents would be willing to have their genetics tested to help doctors diagnose and prevent disease.
"There is no limitation on diseases" that can be treated, said Stacie Propst, director of science policy for Research!America. "Almost everything has some genetic predisposition or some genetic transformation that happens—literally a fingerprint on every one of our conditions or diseases."
Free Email News Updates
Best Online Newsletter, 2006 Codie Awards
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).
SOURCES AND RELATED WEB SITES