Such investigations, typically referred to as "genome-wide association studies," use statistical algorithms to sift through DNA samples and pull out whatever common variations exist that exhibit signs of association with a condition. While powerful, these statistical methods may not shed light on many diseases, says Schork, because not all diseases have such definitive DNA signatures. Many of the most common diseases are more complex. They are associated with multiple genes and multiple environmental factors.
According to Schork, the key to identifying the genetic components of these complex diseases is not to focus on finding single common genetic signatures that people sharebut rather to identify whole collections of rare genetic signatures, any one of which may indicate a predisposition toward a disease.
The situation is analogous to asking how someone from outside New York City could get to Times Square in Manhattan. There is no single answer to that question because there are any number of approaches and modes of transportationfrom New Jersey, from Brooklyn, from Wall Street, or from the Bronx, and via plane, bus, train, taxi, ferry, bridge, tunnel, subway, or sidewalk.
Regardless of where they start or how they get there, it is possible for many people to wind up at exactly the same spot, though, and Schork says the same is true for many human diseases. There may not be one single genetic marker for many diseases, but multiple markers involving any number of genes, even among people who share the same disease.
Finding these rare signatures requires a great deal more scientific sleuthing, says Schork, and in their Nature Review Genetics article Schork and his colleagues suggest a new approach to discover all the possible combinations
|Contact: Mika Ono|
Scripps Research Institute