title: Comparative genomic hybridization.
abstract: Comparative genomic hybridization (CGH) is a screening method based on fluorescence in situ hybridization (FISH). In contrast to conventional FISH, the metaphase target is derived from a normal peripheral blood lymphocyte culture. This target is hybridized to the test or tumor DNA, which is labeled/detected by one fluorochrome (i.e., green), and to an equal amount of labeled normal or reference DNA, which is labeled/detected by a different fluorochrome (red). It is the difference in these green/red ratios (determined by specialized software) along the length of each karyotyped chromosome that indicates the relative copy number changes in the test/tumor DNA. The basic FISH techniques reviewed in this section, the parameters for which also apply to obtaining satisfactory results for CGH, include cytogenetic preparation and slide-making, DNA extraction (from fresh or paraffin-embedded tissues) and labeling, slide pretreatment, hybridization, post-hybridization washes, and detection.
authors.affiliation: Princess Margaret Hospital and The Ontario Cancer Institute University of Toronto, Toronto, Ontario, Canada.
authors.forename: Jane
authors.initials: J
authors.lastname: Bayani
authors.forename: Jeremy A
authors.initials: JA
authors.lastname: Squire
mesh_terms: D020223:Chromosome Painting / Q000295:instrumentation / Q000379:methods*; D002877:Chromosomes, Human / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D004247:DNA / Q000032:analysis* / Q000235:genetics; D015342:DNA Probes; D004273:DNA, Neoplasm / Q000032:analysis / Q000235:genetics; D015894:Genome, Human; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000295:instrumentation / Q000379:methods*; D008214:Lymphocytes / Q000502:physiology; D008856:Microscopy, Fluorescence / Q000295:instrumentation / Q000379:methods*
chemical_list: D015342:DNA Probes; D004273:DNA, Neoplasm; D004247:DNA