UNIT 22.6 Comparative Genomic Hybridization

  1. Jane Bayani,
  2. Jeremy A. Squire

Published Online: 1 JAN 2005

DOI: 10.1002/0471143030.cb2206s25

Current Protocols in Cell Biology

Current Protocols in Cell Biology

How to Cite

Bayani, J. and Squire, J. A. 2005. Comparative Genomic Hybridization. Current Protocols in Cell Biology. 25:22.6:22.6.1–22.6.15.

Author Information

  1. Princess Margaret Hospital and The Ontario Cancer Institute University of Toronto, Toronto, Ontario, Canada

Publication History

  1. Published Online: 1 JAN 2005
  2. Published Print: DEC 2004


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.


  • comparative genomic hybridization;
  • CGH;
  • FISH