Microarray Technology

Introduced commercially in 1994, microarray technology was first used as a research technology in the field of Genomics. Today, it is transforming health care as a powerful, new tool for diagnostic and prognostic applications. Chromosomal translocations, gene mutations and gene expression levels are pivotal information for cancer status and can all be measured in one simple test. Therefore, the potential of microarray technology is now widely recognized and has become an important answer to ever increasing demands for higher standards in diagnostics, including personalized medicine.

In principle, microarrays allow measurement of all known human genes at once – which are currently an estimated 20 thousand. Microarray technology involves a number of principles. First, short DNA sequences complementary to genes of interest, referred to as probes, are to be designed and synthesized. Each probe type is then immobilized on a preselected position on a microarray. Then, isolated RNA molecules from patient sample (e.g. tumor cells) are used to produce cDNA molecules and fluorescently labeled. The fluorescent dye allows detection of where the cDNA molecules hybridized to the immobilized DNA probes, resulting in the information of which genes were expressed in the original (tumor) sample. The intensities of the different fluorescent probe positions can be quantified and reflect the gene expression levels in the original sample. Dependent on the design of the probes, chromosomal translocations, gene mutations and gene expression levels can be measured using microarrays. The specific biochemical nature of the technology and the large numbers of data points retrieved from microarray experiments require advanced analytical methods, which is the realm of Bio-informatics.