What now seems like a long time ago scientists first began to decode the human genome. This accomplishment was heralded as ushering in the era of personalized medicine–making diagnosis and treatment decisions based on an individual’s genetic makeup. Reaching that goal is proving to be elusive and the effect of human genetics on biochemical processes and health is very complex. Research published in Nature describes a detailed examination of 1092 genomes to study the extent and nature of genetic variation. (Nature Article) The study significantly advances the state of the art by identifying many common and unusual variations both generally and within subpopulations and should facilitate linking variation with health consequences. The path from a person’s genome to actual gene expression is not simple; environmental and other factors can affect gene expression. And our understanding of how the genome and gene expression are related to disease and to treatment is in its infancy.
Ideally, one day doctors will be able to have full gene expression data for each patient and will know how that expression will affect their health. In some areas, like drug metabolism, we have a fairly good understanding of how variations in a gene or in expression of those genes affects the effectiveness of the drug for an individual. And some genes are very clearly linked to specific diseases. But for most common chronic diseases, the relationship has not yet been clearly identified. These efforts at personalized medicine have an interesting relationship to the evidence-based medicine and comparative effectiveness movements, which are often rooted more in population health concepts than in individual ones. If we truly care about quality, it seems we should be putting all of our research efforts into personalized medicine and focusing on information that is relevant to each individual patient, not what may work broadly across a population.