DNA Chip as a Tool for Clinical Diagnostics

The identification of the DNA structure as a double-stranded helix consisting of two nucleotide chain molecules was a milestone in modern molecular biology. The DNA chip technology is based on reverse hybridization that follows the principle of complementary binding of double-stranded DNA. DNA chip can be described as the deposition of defined nucleic acid sequences, probes, on a solid substrate to form a regular array of elements that are available for hybridization to complementary nucleic acids, targets. DNA chips based on cDNA clones, oligonucleotides and genomic clones have been developed for gene expression studies, genetic variation analysis and genomic changes associated with diseases including cancers and genetic diseases. DNA chips for gene expression profiling can be used for functional analysis in human cells and animal models, disease-related gene studies, assessment of gene therapy, assessment of genetically modified food, and research for drug discovery. DNA chips for genetic variation detection can beused for the detection of mutations or chromosomal abnormalities in cancers, drug resistances in cancer cells or pathogenic microbes, histocompatibility analysis for transplantation, individual identification for forensic medicine, and detection and discrimination of pathogenic microbes. The DNA chip will be generalized as a useful tool in clinical diagnostics in the near future. Lab-on-a chip and informatics will facilitate the development of a variety of DNA chips for diagnostic purposes.