Thousands of genes and their products (i.e., RNA and proteins) in a living organism function in a complicated way. Traditional methods in molecular biology generally work on a “one gene in one experiment” basis. This means that the “whole picture” of gene function is hard to obtain. A new technology, called DNA microarray, has attracted tremendous interest among biologists. It promises to monitor the whole genome on a single chip so that researchers can have a better picture of the interactions among thousands of genes simultaneously. Currently, genomic micro­arrays are used in medicine to determine the transcrip­tional programs of cells for its cellular function or when cells are exposed to certain conditions leading to activation, inhibition or apoptosis; to compare and contrast tran­scriptional programs as an aid to diagnosis of diseases, predict therapeutic response and provide class discovery and sub-classification of diseases; to identify the genome-wide binding sites for transcriptional factors that regulate the transcription of genes; to predict gene function; to identify new therapeutic targets (target identification, target validation, and drug toxicity); to develop public databases that will help us understand the functions of complex biological systems and, of course, the genetics of gene expression. This is a relatively new field of study and has major implications in complex clinical traits by the identification of promising candidate genes.
Key words: cDNA Microarray, Oligonucleotide array, Genetic Diseases, Cancer, Tumor markers.