ABSTRACT
To understand complex genetic diseases, many biological parameters should be simultaneously interrogated by high-throughput methods. The Human Genome Project in the early 90s made possible the widely spread use of microarray technology, suitable for accomplishing hundreds or thousands of tests at the same time [35]. The advent of cDNA microarray technology led to revolutionary changes in gene expression studies. Introduction of high-density oligonucleotide microarrays enabled transcriptome profiling at the whole-genome level. Recent developments in next-generation sequencing systems (NGS) extended this opportunity even further as previously unknown splice variants can now be quantitatively identified [36]. At the proteome level, in addition to the very important mass spectrometry (MS)-based techniques, advances in microarray technology made protein chips available to examine the target phenotype. Other types of microarrays, such as carbohydrate, lipid, and aptamer chips, are also available to screen posttranslational modifications and metabolic processes. In the following paragraphs, the theoretical basis for microarray technology, the operating principles, and the main application areas to be described also critically point out the limitations of the method. Genomics research provided information on the molecular biology basis of diseases and recognized genes that play important roles in biological processes related to drug treatments. Our knowledge about these genes is continuously growing by utilizing modern mRNA technologies, including Serial
Analysis of Gene Expression (SAGE), microarray methods, and next-generation sequencing (NGS) [35,37,38]. Complementary DNA (cDNA) microarrays can be used to measure changes in gene expression levels and to evaluate gene expression patterns in comparative studies with different phenotypes or physiological conditions. However, as emphasized earlier, DNA microchips are not capable of providing information about changes at the proteome level [39].
