The medical world has known for a long time that one size does not fit all. Two people who take the same anti-cancer drug, for example, may react differently to it. One might develop dangerous, even life-threatening side effects, whereas the other will benefit and experience almost no side effects. The same drug can bring about the disappearance of the malignancy in one patient and have no effect on another. These extreme differences derive from the genetic differences between people. In the same way that a single gene is responsible for different eye colors, a particular gene in different people can lead them to metabolize the same drug either quickly or slowly. People are differentiated from one another in terms of how well a drug is absorbed by the intestines, how well it metabolizes in the liver, how much it secretes in the kidneys - and all these elements determine how much of the drug the individual takes remains in the body and how it will affect him. If the drug metabolizes quickly, its effect will be limited and the dosage will have to be increased. By contrast, if it metabolizes slowly, or is eliminated slowly from the body, it is liable to generate serious side effects to the point of threatening a patient's life.
One of the cardinal contributions of the Genome Project is the knowledge it provides about the scale of genetic diversity. The tremendous technological leap that occurred in the wake of the project now makes it possible to identify the diversity in certain genes. This, in turn, will make it possible to adapt the treatment to accommodate the patient's personal genetic makeup, to accord him the best and safest treatment, to reduce the side effects, to predict the prospects of survival, and more. This is not science fiction. It has already begun to happen. "Personal medicine" signifies not only a trend, but a new sphere in medicine, which is rapidly gaining momentum. In fact, it is one of the hottest subjects in the medical world today, on the agenda of almost every medical conference and described as the medicine of the next generation.
This is clipped from a long story. Not much original to those familiar with the topic, but a convenient summary with a bit of an Israeli perspective.