WASHINGTON — For years, scientists have held out hope that the rapidly evolving field of genetics could transform medical diagnosis and treatment, moving beyond a trial-and-error approach as old as the Hippocratic Oath.

But the vision of individualized treatment based on a patient's genetic makeup and other biological markers has yet to materialize, even if better use of genetic information has led to advances in cancer care and other areas.

Now the pursuit of "personalized medicine" is expected to get a major push from the incoming administration of President-elect Barack Obama. As a senator, Obama introduced legislation to coordinate the sometimes conflicting policies of government agencies and provide more support for private research. He remains keen on the idea.

"The president-elect has indicated his support for both advancing personalized medicine and increasing (research) funding," said Rep. Patrick J. Kennedy, D-R.I., who has introduced legislation in the House that builds on Obama's.

Obama is also interested in the role that personalized medicine could play as an element of changes in the broader health care system.

"The issue of getting the right treatment to the right person goes with his whole emphasis on health reform," said Mark McClellan, a noted Republican health care expert who served President George W. Bush as Medicare director and head of the Food and Drug Administration. "If we're thinking about reforming the health care system, we should be thinking about what medicine will be like down the road when health care reform is fully implemented," McClellan said.

Although medical science is more technologically advanced than at any time in history, in some ways it is still strikingly old-fashioned. For example, most prescription drugs are effective only in about 60 percent of treated patients, leading to a trial-and-error approach to treatment that not only may be more costly, but can put some patients at risk.

Among patients, the varying responses to medications may be linked to differences in genetic makeup that affect how the body processes a drug. For example, the FDA recently warned that certain drugs for epileptic seizures may prompt a severe skin reaction in Asian patients because of a genetic trait. The practice of medicine could be streamlined if doctors had reliable ways of predicting which drugs would work on which individuals.

Government funding for research helped make possible many of the scientific gains in genetics, and Congress has passed landmark legislation outlawing discrimination against patients on the basis of genetic information.

But the mundane decisions, such as whether or not to pay for some genetic tests, have not progressed that smoothly.

For example, the FDA supported research that found certain genes can make some patients taking the blood thinner Coumadin susceptible to potentially fatal bleeding. The agency has been pushing for some time to make doctors aware of genetic tests that could help their patients.

But Medicare has not yet set a national policy on paying for the tests. Problems with Coumadin, also known as warfarin, are a major cause of emergency room visits for seniors.

"It would be very helpful if you could get (Medicare) and FDA talking to each other," said Edward Abrahams, executive director of the Personalized Medicine Coalition. "Right now they really don't communicate very well, and they have different agendas. The federal government is not coordinated around removing the barriers to personalized medicine." His group represents university research centers, industry and patients.

Obama's legislation would create an interagency group to coordinate the policies of federal agencies whose decisions have an impact on the issue. Kennedy also would direct Medicare to set a fixed policy for coverage of genetic tests and treatments.

Both bills would establish a national 'Biobank' to pool data that could serve as a resource for scientific researchers, and the legislation also calls for increases in federal funding. Obama has proposed a 100 percent tax credit for private research to develop diagnostic tests that can predict the safety and effectiveness of certain high profile drugs.

"So far, we haven't really seen any transformation of medicine," said McClellan. "There are some real questions to deal with to see if there is some policy that could speed it up.