Recently, a new technology, called microarray, has been developed.  A microarray analysis compares a person’s DNA to “control DNA”.  The control DNA comes from a person that doesn’t have a chromosome abnormality.  A chromosome change is identified when there are differences between a person’s DNA and the control DNA.  Sometimes, it can be difficult to interpret microarray results.

Microarrays are useful in that they are able to detect much smaller changes than routine karyotypes.  They tell us if there are changes in the amount of DNA present.  They can identify deletions or duplications as well as unbalanced translocations.  However, microarrays cannot diagnose balanced translocations.  This is because microarrays can only determine how many copies of each piece of the chromosomes are present.  Microarrays cannot tell us how the chromosomes are arranged.  If two chromosome regions have swapped places, but there are no extra or missing pieces of chromosome material, you would only be able to see that change on a karyotype. This is because there is no change in the amount of DNA present, only a change in location and arrangement.

In general, microarray technology can also be used to learn more precise information abnormalities that have already been diagnosed by karyotype.