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Chromosomal Microarray Testing

In Patients with Development Delay, Autism or other Congenital Anomalies



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Limitations of Chromosomal Microarray

Slide 7

September 2011

Every assay, of course, has limitations. The limitations of chromosomal microarray testing are that truly balanced rearrangements such as balanced translocations or inversions are not detectable with this assay-only unbalanced rearrangements are detectable. The other major disadvantage of chromosomal microarray testing is that it does not provide information on the structural nature of an imbalance. This type of information requires a second method and typically we utilize FISH testing to visualize the exact locations of deletions and duplications. This is very useful for defining unbalanced translocations and also differentiating between tandem duplications and insertional translocations.

This slide demonstrates an insertional translocation. The green probes are the centromere of chromosome 12 and the red probes are on distal chromosome 12q and you can see that there is an additional set of red signals and this actually is an insertional translocation into chromosome 2. This is a relatively rare type of rearrangement but it illustrates very well the utility of FISH testing to follow up what we would see on the array as a gain of multiple probes.

Limitations of Chromosomal Microarray

 


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