Molecular - Microarray - Comparative genomic hybridization

Home Chapter Home Jobs Conferences Fellowships Books

Molecular Pathology

Microarray

Variations - Comparative genomic hybridization

Author: Rodney E. Shackelford, DO, Ph.D. (see Reviewers page)

Revised: 3 July 2010, last major update July 2010

General

=========================================================================

● Comparative Genomic Hybridization (CGH) is used to detect copy number changes (amplifications or deletions) of relatively large genomic segments

● CGH only detects unbalanced chromosomal changes; balanced chromosomal alterations, such as inversions and translocations are not detected, as no change in copy number occurs

Methodology

=========================================================================

● Control DNA is taken from cells with a normal karyotype and compared to the sample to be examined

● The examined sample is often from a tumor or tissue from a child with dysmorphic features who is likely to have unknown genomic amplifications or deletions

● Originally, CGH was done with fluorescent-labeled metaphase chromosomes immobilized on glass slides, co-hybridized with different fluorescent-labeled control and sample DNA

● Comparison of the different preparations and fluorescent labels allows the identification of changes in the copy number along specific chromosomal regions

● The resolution of this approach is low, allowing only changes of 20 Mb or more to be identified (DNA Microarrays for Biomedical Research: Methods and Protocols; Humana Press, 2009)

● Currently array CGH is more commonly used to analyze amplifications or deletions between sample and control cells; it uses an immobilized probe array, to which are hybridized differently labeled normal and sample DNAs; the resolution depends upon the number of immobilized probes employed

● CGH allows only the comparison of the relative ratio of different DNA segments between samples and controls, not the ploidy; thus, comparing two tetraploid clones lacking amplifications or deletions by CGH would give a normal result

End of Molecular Pathology > Microarray > Variations > Comparative genomic hybridization

This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must also be interpreted in the context of a patient's clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician.

All information on this website is protected by copyright of PathologyOutlines.com, Inc. Information from third parties may also be protected by copyright. Please contact us at copyrightPathOut@gmail.com with any questions (click here for other contact information).