THE PHYSICAL OF THE FUTURE

“I SEE THIS is your first visit,” says the doctor, looking up from her notes. “What seems to be the problem?” With a shuddering sigh, you describe your lack of energy, inability to sleep, disinterest in activities you once found pleasurable, and the crying—every day you cry. “Have you ever been treated for depression?” she asks, reaching for what looks like a small plastic tongue depressor. “Uh-uh,” you gurgle, mouth agape, as the doctor scrapes a swath of cells from inside your cheek. “Then we’ll just do a quick ‘snip check,’ and you can pick up your prescription this afternoon,” she says, dropping the spatula into a vial and sending it off to the laboratory. There technicians will extract and analyze your DNA to determine which of the 837 antidepressants on the market will best chase away your blues.

Will pharmacogenomics usher in such an era of personalized medicine, in which our genetic fingerprints will determine the kind of medical treatment we receive? Will every trip to the clinic involve surrendering some DNA for sequencing? And once our DNA sequences can be easily accessed from a global database, will physicals be replaced by phone-ins?

Well, yes and no. First, it is important to keep in mind that genes aren’t everything. “Many factors determine drug response,” cautions William A. Haseltine of Human Genome Sciences. Genes are important, but so are the age, sex and general health of the patient, as well as the other drugs he or she might be taking. Still, scientists anticipate that genetic profiling may soon help doctors diagnose diseases and allow them to prescribe medications that will work best for an individual patient. “Most drugs only work on 30 or 40 percent of people,” says Daniel Cohen of Genset in Paris. “Only aspirin works on almost everyone.”

Genetic testing should help match the right drug at the right dose to the right patient without a lot of time-consuming trial and error. If you were clinically depressed, for example, a quick look at the results of a test called a P450 profile might indicate that you break down drugs so rapidly that you would probably clear certain antidepressants from your bloodstream before they could take effect. Or you might break them down so slowly that normal doses would make you antsy.

In addition to helping determine drug dosage and minimizing unwanted side effects, genetic screening may soon be used to predict a patient’s predispositions to disease. Perhaps when you’re 18 years old, you’ll automatically be screened for your susceptibility to heart disease, diabetes, Alzheimer’s disease, cancer and scores of other disorders. Armed with this knowledge, you might then be able to change the way you live or the foods you eat to boost the odds that you’ll stay healthy.

Will we all eventually carry plastic plates the size of credit cards that are digitally encoded with all the genetic secrets stored in our genomes? “No, they’ll probably be on chips implanted under our arms,” jokes John Tallman, Neurogen’s executive vice president. Although both options may someday be technologically possible, they will probably be a ways off. For one, investigators have yet to sequence one complete human genome. So rather than sequencing every one of the six billion nucleotide letters that make up your personal genetic code, for now pharmacogeneticists will very likely focus on the few hundred gene mutations, or SNPs, that have been shown to correlate with drug responsiveness or disease risk, says Francis S. Collins of the National Human Genome Research Institute. Ultimately, researchers hope such tests will cost a few dollars and yield results in an hour. Genetic testing, of course, raises privacy issues. Will your employer or insurer be able to access your genetic profile? What about telemarketers? With any luck, legislators will pass laws designed to protect your genetic privacy long before the technology makes this future possible. Still, imagine answering the phone during dinner to hear a chirpy electronic voice dispense unwanted medical advice: “Isn’t it time you started taking Progenitol?”