Biochips – fundamentals and applications - Electrochemical Sensors, Biosensors and Their Biomedical Applications - page 328

ScanAlyze ImaGene GenePix

FIGURE 11.23

Common approaches to local background methods.

11.2.6 Applications
DNA arrays are useful for a variety of genomic applications, including single nucle-
otide polymorphism (SNP) analysis, gene expression studies, disease classifi cation,
function prediction, pathway identifi cation, new drug development, clinic diagnos-
tics, and toxicology studies. Perhaps the greatest driver of the DNA array market is the
demand for speed and high throughput. The ability to look at thousands of genes in a
single experiment will increase the speed of drug-target identifi cation and validation,
as well as decrease the time required for optimizing lead drugs.
Gene expression profi ling is the leading application in the biomedical research cate-
gory, due to biochips' potential to simultaneously monitor genes expression in diseased
cells and cells that are healthy. Gene expression profi ling has enabled the measure-
ments of thousands of genes in a single RNA sample. RNAs are labeled with fl uores-
cent dyes and hybridized on the biochip. Hybridization between the sample RNAs and
the reference RNAs under different environmental conditions allows scientists to com-
pare gene expression under different conditions such that groups of genes that play a
role in disease processes can be identifi ed.
In the drug discovery process, researchers may be interested in the gene expressions
under the conditions of the presence or absence of drugs. Tens of thousands of mRNAs
in a large number of samples are monitored. The differences in gene expression also
provide a drug marker with unique targets that are present only in diseased cells. Using
DNA biochips, labor and reagent cost can be reduced by a great magnitude. In the
case of cancer, oncogenes and proto-oncogenes are activated. On activation, proto-
oncogenes become tumor-inducing agents - an oncogene, leading to the possibility of
cancer. Oncogenes and proto-oncogenes do not occur in healthy cells; therefore, tar-
geting these genes may lead to new therapeutic approaches.
Some of the gene expression profi ling analysis biochips on the market include
Affymetrix's standardized GeneChip for a variety of human and yeast genes and HyX
Gene Discovery Modules for genes from tissues of the cardiovascular and from tissues
that are germ infected.
Single nucleotide polymorphism (SNP) is a variation of the genetic sequence (point
mutation) when a single nucleotide in the DNA is altered. It has a 0.1% chance of