Postgenomic Medicine: The Evolution of Clinical Medicine -- and the Clinician

Bryan Bergeron, MD

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In This Article

Introduction

Despite the technology that we use to evaluate our patients, clinical medicine is largely a contact sport; most diagnoses can be made with a good thorough history and physical. However, our understanding of the mechanism forming the basis of diagnosis -- and the rationale for the most appropriate treatment -- is typically based on discoveries made by using technology focused on a particular disease. For example, our relatively recent appreciation for bacteria as the source of infection was dependent in part on our ability to observe bacteria first through optical, and then electron, microscopes. As our ability to see or visualize the finer details of life increased, down to the molecular structure of the genes and proteins that form the basic building blocks of life, so has our appreciation for the genomic basis of disease.

Consider that when Isaac Newton was struggling to understand the laws of gravity through objects such as apples, he could only go so far in developing classical or Newtonian physics. Advances in physics during the latter half of the past century, from lasers and atomic energy to nuclear magnetic resonance imaging, required the visualization and understanding of subatomic particles. Similarly, traditional clinical medicine has been limited by our reliance on gross measures, such as lab values and visible anatomical changes. However, this is rapidly changing, given our ability to sequence the genome, visualize the 3D structure of proteins, and model the complex interaction of proteins.

Today, much of the focus of medical research is on the genome and proteome -- how our DNA, and the protein it codes for, interacts with the environment to define overall health, longevity, and response to drugs. Our understanding -- and treatment -- of diseases from HIV and cystic fibrosis to diabetes is now at the level of DNA and the expression of certain genes. Clinicians -- and their Web-savvy patients -- are becoming aware of the significance of a patient's genome in everything from the patient's response to anesthetics to the advantage of certain genetic "disease" mutations. For example, the mutation responsible for cystic fibrosis, like the mutation responsible for sickle cell anemia, confers an advantage on the carrier of a single copy of the mutation, even though the homozygous state isn't compatible with a long, healthy life.

It's only a matter of time before we're routinely using gene chips in our clinics. Dozens of biotech companies are offering thumbnail-sized matrices that can detect specific gene sequences related to particular diseases. While these companies undergo the usual cycle of introduction and clinical trials, it behooves every clinician to understand medicine from the perspective of genes and proteins, lest we become relegated to mere technicians practicing cookbook medicine. Before considering the practical insights now possible by understanding the genomes and proteomes of humans, pathogens, and laboratory animals, let's take a step back and examine the development of genomic and proteomic medicine from a historical context.

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