It allows researchers a panoramic view of cancer gene expression, thousands of genes at a time. We now can step back and take inventory on a larger scale, which nicely complements our traditional approach of examining suspect genes one at a time. Watson and his colleagues already have begun to classify tumors using this method and are compiling genetic profiles that may help predict clinical behavior and response to therapy. Perry uses specially designed fragments of DNA to probe individual tumors for specific genetic regions of interest. These DNA probes deposit a red or green fluorescent dye wherever those genetic regions are present and these colored signals, or dots, are then visible through a microscope.
Normal cells have two copies of each gene.
Either of the latter two scenarios might indicate tumor growth. But by adding techniques like FISH, we'll be able to get a lot more information from our diagnosis that will be useful to the patient. His optimism is well-founded. For years, researchers have been puzzled by one form of brain tumor called oligodendroglioma. Though most patients with oligodendroglioma respond well to chemotherapy, a significant percentage do not.