The first steps in the Human Genome Project are to develop the needed technologies, then to "map" and to "sequence" the genome. But in a sense, these well-publicized efforts aim only to provide the raw material for the next, longer strides. The ultimate goal is to exploit those resources for a truly profound molecular-level understanding of how we develop from embryo to adult, what makes us work, and what causes things to go wrong. In the offing is a new era of molecular medicine characterized not by treating symptoms, but rather by looking to the deepest causes of disease. Rapid and more accurate diagnostic tests will make possible earlier treatment for countless maladies. Even more promising, insights into genetic susceptibilities to disease and to environmental insults, coupled with preventive therapies, will thwart some diseases altogether. New, highly targeted pharmaceuticals, not just for heritable diseases, but for communicable ailments, as well, will attack diseases at their molecular foundations. And even gene therapy will become possible, in some cases actually "fixing" genetic errors. All of this in addition to a new intellectual perspective on who we are and where we came from.
But how is it possible, with the incredible diversity of the world's five and a half billion people, to determine an "average" genome that can be considered even reasonably accurate? The answer lies in an understanding that DNA, with its millions of base pairs, is not the workhorse of the human body -- proteins are -- and that the body is built and run with fewer than 100,000 different kinds of protein molecules. For each of these proteins, we can imagine a single corresponding gene composed of many base pairs (though there is sometimes some redundancy), whose job it is to ensure an adequate and timely supply of the structural or regulatory materials. In a very real sense, then, all of the subtlety of our species, all of our art and science, is ultimately accounted for by a surprisingly small set of discrete genetic instructions. More surprising still, the differences between two unrelated individuals, between the man next door and Mozart, for example, may reflect a mere handful of differences in their genomic recipes -- perhaps one altered word in five hundred. We are far more alike than we are different. At the same time, there is room for near-infinite variety.
It is no overstatement to say that to decode our 100,000 genes in some fundamental way would be an epochal step toward unraveling the manifold mysteries of life û but only if we understand what those genes produce and how they regulate that production. It is the difference between seeing a string of letters on a page and recognizing which of those letters actually form words, and which of those words form sentences. Meaningful information only derives from the relationship between the words to form discrete ideas.
