Cytogenetics In the Department of Pathology


Array Comparative Genomic Hybridization (aCGH):

Array comparative genomic hybridization (aCGH) is a new method using existing array technology to detect some chromosomal abnormalities that are too small to be appreciated by high resolution chromosomal analysis.  Typically, high resolution chromosomal analysis can detect chromosomal abnormalities of between 5 to 10 Mb in size.  Depending upon the type of array and the spacing of the features on the array, the size of detectable anomalies can be anywhere from a few hundred kilobases of DNA to less than 5 Mb.

Our method utilizes a microarray carrying 105,000 oligonucleotide (Agilent) sequences from known genomic locations at an average spatial resolution of 35 kb of DNA.    Patient and control DNA samples are labeled using different fluorescent tags.  These DNA samples are then hybridized to the array.  The arrays are scanned and the intensities of the fluorescence are plotted as a ratio at each oligonucleotide probe.  These ratios can then be interpreted as representing either a loss or a gain of DNA.  A copy number change is considered only when three or more adjacent oligonucleotides are shown to be duplicated or deleted (with an average size of ~ 100 kb).

Please note:  This array cannot detect polyploidy, balanced chromosomal rearrangements, mosaicism, small duplications or deletions below the resolution of this array or point mutations.  The clinical significance of any anomaly discovered by this array may be unknown. 


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