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Breen, Matthew, PhD. C.Biol. M.I.Biol
Associate Professor of Genomics
Comparative Genomics Hybridization (CGH)
Whilst the use of metaphase FISH, and interphase FISH are highly suited to the identification of chromosome translocations and inter-chromosomal insertions, chromosome aberrations such as deletions and amplifications are best visualized using Comparative Genomics Hybridization (CGH) analysis. This is an ‘indirect’ approach that provides, in a single FISH reaction, a detailed and accurate analysis of imbalanced chromosomal material within an entire genome. Since CGH is a technique that requires only the DNA isolated from the tumor cells, there is no essential prerequisite to obtain viable cancer cells. This enables CGH analysis to be performed using DNA prepared from fresh tissue and also archival tumor material including frozen tissue samples and suitable paraffin embedded pathology specimens. CGH may also be regarded as a low-resolution whole genome scan, identifying large regions of the genome that may contain genes or loci associated with the initiation and/or progression of cancers. There are two forms of CGH analysis, metaphase-based CGH and array CGH. Both forms are based on the same concept as illustrated below.