Although billions and billions is a daunting quantity, the reality of these studies are data sets with trillions and trillions points, or whatever 106 x 105 winds up to be (that’s the number of SNPs times the number of people tested). I have trouble keeping track of experiments with 96 wells in an ELISA plate or 12 lanes in a Western blot. No way could I manage the mass of data needed to harvest, as the geneticists put it, the low-hanging fruit, let alone the high-hanging fruit that a modern genome-wide association study makes possible.
I can just imagine a conversation like the following: ‘Well, Mr. Jones, we just ran your genome and we have good news and bad news. The good news is that you have a cytosine at position number 163 of your TNF gene. The bad news is that it is methylated.’ Good luck in explaining that one.
Benefits of Personalized Medicine?
As several of the speakers at the meeting stated, we are about to enter the era of personalized medicine in which science can predict the likelihood of disease for that part of etiology that is genetic in origin. Much of disease etiology is environmental and for that prediction is less good. Nevertheless, soon we can tell people about their risk for developing rheumatoid arthritis or lupus, assuming that they want to know. Risk profiles will likely only be relative, but such information could be valuable in planning strategies for prevention.
At this point in personalized medicine, things get uncertain because current strategies for disease prevention are limited and often difficult to implement. We all know that the arrows in the quiver of prevention are few: exercise, don’t smoke, don’t eat, and don’t drink (unless you are French, in which case you can guzzle the red stuff until you are 100). Alas, unless you want to stay hermetically sealed in a space suit, bugs of all kind will come your way and mess with your toll receptors, potentially stirring up the mischief known as inflammatory and autoimmune disease.
Hot on the heels of the genetic revolution is the epigenetic revolution. Epigenetics refers to the modification of genes, such as base methylation, which determines how genes are switched on and off. Thus, even if two individuals are genetically identical, changes in the epigenome may determine how heredity plays out to affect the risk for disease. Indeed, as one of the speakers at the meeting described, identical twins discordant for lupus show distinct patterns of base modification in their expressed genomes.
