The disease process is a complex one with both endogenous and environmental contributions. Many subtle changes contribute to a disease’s existence, its severity, and its course. There is often more than one way to get to the pathological state to begin with, a reason for splitting symptom clusters (known as syndromes) into multiple diseases. Thus developing drugs to treat potentially small numbers of patients will be highly complex and costly. So the key issue for potential investors in personalized medicine becomes: will medicine evolve in the direction of systematic applicability of “gating” tests and custom drugs, or remain locked in the broad applicability of chronic disease therapeutics?
