DNA chips: the future of biomarkers

DNA chips are small, solid supports such as microscope slides onto which th ousands of cDNAs or oligonucleotides are arrayed, representing known genes or simply EST clones, or covering the entire sequence of a gene with all it s possible mutations. Fluorescently labeled DNA or RNA extracted from tissu es is hybridized to the array. Laser scanning of the chip permits quantitat ive evaluation of each individual complementary sequence present in the sam ple. DNA chip technology is currently being proposed for qualitative and quantit ative applications, firstly for the detection of point mutations, small del etions and insertions in genes involved irt human diseases or affected duri ng cancer progression; secondly, to determine on a genome-wide basis the pa ttern of gene expression in tumors, as well as in a number of experimental situations. The extraordinary power of DNA chips will have a strong impact on medicine in the near future, both in the molecular characterization of tumors and ge netic diseases and in drug discovery and evaluation Quantitative applicatio ns will soon spread through all fields of biology.