Method
DNA from subject tissue and from normal control tissue (reference) are each labeled with different tags for later analysis by fluorescence. After mixing subject and reference DNA along with unlabeled human cot-1 DNA (placental DNA that is enriched for repetitive DNA sequences such as the Alu and Kpn family) to suppress repetitive DNA sequences, the mix is hybridized to normal metaphase chromosomes or, for array- or matrix-CGH, to a slide containing hundreds or thousands of defined DNA probes. Using epifluorescence microscopy and quantitative image analysis, regional differences in the fluorescence ratio of gains/losses vs. control DNA can be detected and used for identifying abnormal regions in the genome.
Currently, strategically placed oligonucleotides offer a resolution typically of 20–80 base pairs, as compared to the older BAC arrays offering resolution of 100kb.
Read more about this topic: Comparative Genomic Hybridization
Famous quotes containing the word method:
“As a science of the unconscious it is a therapeutic method, in the grand style, a method overarching the individual case. Call this, if you choose, a poet’s utopia.”
—Thomas Mann (1875–1955)
“It is to be lamented that the principle of national has had very little nourishment in our country, and, instead, has given place to sectional or state partialities. What more promising method for remedying this defect than by uniting American women of every state and every section in a common effort for our whole country.”
—Catherine E. Beecher (1800–1878)
“The method of political science ... is the interpretation of life; its instrument is insight, a nice understanding of subtle, unformulated conditions.”
—Woodrow Wilson (1856–1924)