Impacts of DNA Microarray Technology in Gene Therapy

Invention of microarray technology in the early 1990s revolutionized the genomic research, where it was exploited for global gene expression profiling through screening the expression of thousands of genes simultaneously (Watson et al., 1998). Northern blotting and reverse transcription polymerase chain reaction (RT-PCR) which were the traditional techniques for monitoring changes in mRNA levels were replaced with high density arrays, which proved to impart comprehensive data and to be better in the course of time. Nowadays, microarrays are used for genotyping, large scale single nucleotide polymorphism analysis, comparative genomic hybridizations, identification of new genes, establishing genetic networks and as a more routine function, gene expression profiling (Bednar, 2000). Providing a unique tool for the determination of gene expression at transcriptomic level, it confers simultaneous measurement of large fractions of the genome which can facilitates the recognition of specific gene expression patterns associated with a certain disease or a specific pharmaceutical. Detection of the inimitable genomic signature of any active compound is deemed to be another important application of microarray technology, upon which “intrinsic genomic impacts” of any pharmacologically active agent can be clarified. And presumably, such toxicity predication may promise notable information about each individual resulting in unique patterns of gene expression that, in turn, exhibit individual specific responses to a particular toxic substance. Basically, the discovery of diagnostic biomarkers has been the most promising feature of microarrays up to now and microarray technology has shown a great potential in predicting gene function and tracking the interactions among genetic networks too (Xiang & Chen, 2000). Microarray methodology has also been applied for analysis of proteins and metabolites, which are the principle controllers of gene expression, to verify the results at the molecular level. This in turn can extend our understanding of gene expression patterns and molecular pathways even though other techniques such as NMR, mass spectroscopy, gas and liquid chromatography can be employed for metabolite profiling. Having exploited such techniques, for example, the identity and quantity of different molecules can be determined in the CSF, urine or any other biological sample. Thus, by merging the classical techniques with new high-density microarray, the “omics” technology has been devised and