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Chromosomal Microarray Testing

In Patients with Development Delay, Autism or other Congenital Anomalies



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Chromosomal Microarray Testing

Slide 4

September 2011

There is more than 1 type of chromosomal microarray testing. At Mayo we use a technique called array comparative genomic hybridization or array CGH. The current array platform that we use in the clinical lab has approximately 50 fold higher resolution than a chromosome study and in the same population of patients, this technique detects chromosomal abnormalities in 15 to 20% of patients as opposed to 4%. I’ll go through the technique briefly. DNA is extracted from both a patient and a control. Both patient and control DNA are labeled with different fluorescent dyes, mixed, and cohybridized to the chip containing arrayed oligonucleotide probes. Following approximately 24-hour hybridization and washing steps, the arrays are scanned at approximately 2 micron resolution and the data are plotted on a log2 scale as shown on the next slide.

So this is an example of our current array that is in use clinically in the laboratory. There are 4 blocks on the array each representing a hybridization site for a single patient so we can analyze 4 different patients on the same microarray. Each of those blocks contains approximately 180,000 individual oligonucleotide probes and you can see individual differences in each spot on this array in various colors of red and green.

Chromosomal Microarray Testing

 


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