DNA Arrays in Many Guises

Abstract

DNA arrays, first described in 1995, were an immediate success and, for a while, represented the only really large-scale technology available for biology. They quickly evolved towards increased complexity, better quality and lower price, thanks largely to industry involvement. In research settings, they were at first essentially used to obtain expression profiles, but their major use today is in genome-wide association studies of complex diseases. Clinical applications fall into two major categories: expression profiling of tumours to predict cancer recurrence and orient treatment, and genotyping (DNA) studies. The latter can be focused on characterisation of pathogenic organisms or, alternatively, on examination of the patient’s DNA to assess for the presence of specific mutations as well as of copy number variations (CNVs) that may have medical significance. These applications are briefly discussed here and then presented in more detail in the following three chapters (expression, genotyping and copy number variation, respectively).