Imagine visiting your doctor for all annual exam--only this time the checkup begins not with a physical but with a routine sequencing of your genome(基因组)． Using information from the test, you physician not only diagnoses the diseases you are most susceptible to but also selects the types and doses of medication best suited to help you combat the maladies．It’s called personalized medicine．The term broadly refers to the detection, treatment, and prion of diseases based on a person’s unique genetic makeup, and many people believe it will revolutionize health care．
"When you go to your physician ten years from now virtually all of the decisions about diagnosis and treatment will be based on individual information about your particular circumstance as opposed to a more general kind of approach to lots of other people in your general circumstance, "said genome expert Francis Collins．Collins 1ed the international effort to sequence the human genome, which was completed in 2003． That effort was followed by the creation of a map of human genetic variation．
The genome contains tens of thousands of genes, which code for proteins and other molecules that make life possible．Although there are some three billion"letters" in the human DNA code, 99.9 percent are identical between any two people．The small remaining differences hold clues about why people tend to develop particular diseases．
"We now have the technology to assess in people with disease, versus those who don’t have the disease, which of those genetic variances seem to be overrepresented, Collins said"we are on the brink of discovering what are the hereditary(遗传的) factors in diabetes, heart disease, in the common cancers, high blood pressure, asthma, mental illness--virtually any disease you can think of that tends to run in families"
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(范例)," 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(抗抑郁剂) drugs such as Eli Lilly’s Prozac.
What can we know about human DNA from the passage