Genomic Medicine

The idea of preventive medicine is not new, but until the completion of the Human Genome Project medicine did not have a way of accomplishing it for common medical problems. For example, for years almost every baby born in the United States has had its urine or blood screened early in life for phenylketonuria (PKU), a rare genetic disease in which affected individuals cannot metabolize the amino acid phenyalanine, a common amino acid in our food. Untreated, PKU patients develop severe mental and psychomotor retardation. However, if a child is identified early in life to have the PKU mutation, the disease can be prevented by placing the child on a special diet that lacks phenylalanine.

Genomic medicine technique will not look at just one gene or protein in an individual. It will also look at the interaction of thousands of genes at once, using DNA chips or microarrays. These microarrays are already being used in cancer chemotherapy to predict which drugs will work best on each patient's specific tumor.

Therefore, in the future an individual will be able to go to the doctor for a regular checkup and give a small sample of blood, or maybe even just let the doctor take a mouth swab. This will provide a DNA sample that would then be placed on a genetic "microchip" or other device and quickly be genotyped to give a genetic profile of the patient. The doctor will use the information to tailor the medical treatment for that patient. Lifestyle changes or medicine will be suggested to prevent the occurrence of diseases to which the patient is genetically susceptible, or at least to reduce the risk or severity of such diseases. If medication must be prescribed, the doctor will also use this genetic profile before choosing the medicine, to make sure that "the right medicine for the right patient" is chosen: one that works and will not harm the patient or cause side effects.

These changes in medicine are likely to take place over the first half of the twenty-first century. They will be exciting, but they will require that both patient and doctor have a strong understanding of genetics, the most powerful future tool of medicine.