What is Drug Discovery

A major challenge in the post-genomic era is to understand the specific cellular functions of individual genes and how dysfunctions of these genes lead to different diseases. As an emerging area of systems biology, gene networks have been used to shed light on gene function and human disease. In this chapter, first the existence of functional association for genes working in a common biological process or implicated in a common disease is demonstrated. Next, approaches to construct the functional linkage gene network (FLN) based on genomic and proteomic data integration are reviewed. Finally, two FLN-based applications related to diseases are reviewed: prediction of new disease genes and therapeutic targets, and identification of disease-disease associations at the molecular level. Both of these applications bring new insights into the molecular mechanisms of diseases, and provide new opportunities for drug discovery.