The DNA Differential
What will the fully realized pharmacogenomics revolution in medicine bring us? Numerous questions involving health insurance and other nagging ethical, political and social issues must be confronted over the next decade (see “Yourgenome.com” sidebar). But eventually knowledge of the relevant variations in your own genome-perhaps via a readout in your doctor’s office using a biochip-will provide predictions of your potential health problems before they happen. To start with, there will be indications of whether a particular medication might have toxic side effects for you, based on your DNA. Then there will be prescriptions specifying which of the many pharmaceutical and other health care options will be optimal for you. Finally, physicians will be armed with genetically targeted medications, advice for behavior change and other elements of what Nicholas Dracopoli, executive director of the Pharmacogenomics and Human Genetics Group at Bristol-Myers Squibb, calls “disease management packages.” This will allow doctors to intervene well in advance of symptoms, so tumors won’t form, arteries won’t clog, bones won’t grow brittle and aging brain cells won’t die.
Before we reach this payoff, several key technological challenges must be overcome (see “Breakthroughs Ahead” sidebar on next page). The first is to identify as many of the small genetic variations between individuals as possible. These variations, known as single nucleotide polymorphisms (SNPs), are simple chemical substitutions of one letter of the DNA alphabet for another in a person’s genes; though “minute,” these substitutions can make a world of difference in how a person responds to a given medication. Yet not all SNPs actually have much medical significance, and sorting out the important from the unimportant is another crucial technological challenge.
Sidestepping Side Effects
Even before these technological problems are conclusively solved, the first steps toward personalized medicine are already being taken. Indeed, two waves of innovation are likely before the full array of “disease management packages” are in place. The first wave includes genetic tests to predict which patients will suffer “adverse reactions,” the sometimes fatal side effects caused by drugs.