Moving Closer to Personalized Medicine

The sequencing of a scientist's genome is one new advance toward a world of personalized healthcare.

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Popping into a health clinic and emerging with the full details of your genome is in the realm of science fiction. But an achievement announced this month—the first publication of the complete genome of a single person—has perhaps moved the world closer to such a day, when each person's healthcare might be personalized to accommodate his or her genetic quirks.

"This is just a first step. I would predict that over time there will be more and more people having their genomes sequenced," said Robert Strausberg, deputy director of the Venter Institute. He and his colleagues published the genome of the institute's founder, J. Craig Venter, in the journal PLoS Biology. Someday, genome sequencing "will become part of standard healthcare," Venter predicts.

Some medical researchers imagine a future in which much medical care will take place before people ever get sick, using tests that identify variants of genes and proteins and differences in metabolism that could predispose a person to disease or affect how he or she responds to a medication. "Medicine ought to be targeted to individuals," says Edward Abrahams, executive director of the Personalized Medicine Coalition, a nonprofit organization that advocates the use of genetic and molecular tests. "One size doesn't fit all anymore."

In some ways, genetic testing is already a critical component of medical care. Genetic screening is routinely used to diagnose genetic disorders such as Huntington's disease, to screen couples for genetic conditions they might pass on to children, and to determine whether certain drugs will be effective in a particular patient.

In August, the Food and Drug Administration for the first time recommended the routine clinical use of a genetic test. The test, sometimes referred to as a warfarin sensitivity test, can identify genetic differences between people in how they metabolize the anticlotting drug warfarin, which is also known by the brand name Coumadin. People who metabolize the drug quickly are at a high risk of experiencing an overdose from a quantity of the drug that wouldn't cause problems in someone else. Accidental warfarin overdoses lead to more emergency room visits than overdoses of any other drug except insulin, according to the FDA. Testing can help doctors determine each patient's proper dosage.

The real promise of genetic diagnostics may be the prospect of applying them to the prevention of common conditions such as diabetes and heart disease. If a genetic test could determine that a particular person is at high risk of diabetes, for example, lifestyle changes and preventive drug treatments could stave off the illness. So far, though, genetic tests for those diseases remain unavailable. Developing them is challenging, because the diseases aren't caused by one faulty gene, but rather by a complex interplay among multiple genes, diet, lifestyle, and environment. However, new types of studies that examine how multiple genes work in concert to affect disease risk have opened new avenues that could lead scientists to better understandings of complicated conditions, says Greg Feero of the National Human Genome Research Institute. Such studies, says Feero, have provided "a flood of information about genetics of very common disorders."

It will take time for researchers to digest that flood of data and use it to invent genome-based clinical tests. But assuming they can—and many believe they will—having one's genome sequenced could become a standard facet of healthcare. "As we learn more about the causes of diseases and the relationships between disease, the genome, and the environment," says the Venter Institute's Strausberg, "medicine will move toward developing the right prevention strategy for an individual."