How DNA microarrays and expression profiling will affect clinical practice

In Plato's cave the participants are surrounded by shadows that allow them to see reality by careful examination. Similarly, we doctors at the end of the 20th century have found many indirect tests that allow us to follow what is happening in our patients' bodies and cells. We have learnt to cope with the fact that we cannot find drugs unless we pull proteins from those cells and develop inhibitors against them in the artificial context of a test tube. Imagine now a different world in which it would be possible simultaneously to follow many changes that were happening in cells. Imagine a doctor's office where you could take a blood sample from a patient and get an indication of where that patient's heart disease, kidney disease, and depression were plotted in a matrix, allowing us, as doctors, to see both the patient's relative state of health and any predisposition for other conditions or disorders.

Some of the most exciting developments in the field of diagnostics and therapeutics are occurring in the adjacent fields …