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Chromosomal Microarray Testing

In Patients with Development Delay, Autism or other Congenital Anomalies



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Pretest Counseling

Slide 13

September 2011

Since it is always possible that a copy number change of uncertain significance will be found, it is important that families are aware of this possibility. This anticipatory guidance can be immensely helpful to families if they have to deal with a test result of uncertain significance. Describe the possible test results to them. A pathogenic change is one that we know would impact the child’s health and likely explain his or her problems. In discussing uncertain results, it is very helpful to explain that we all have some gains and loss of genetic material that is just part of normal variation and that parental testing is sometimes needed to help understand the significance of a child’s result. Sometimes, even with this information we may not sure. And finally a normal result, in which case there may be a need for further testing or evaluations. I’d also like to point out that if the clinician is aware of the potential of nonpaternity, the lab needs to be informed of this.

Another reason it is important to discuss possible parental testing up front is that some parents may be afraid of the possibility that they may have passed down a genetic cause for their child’s problems. They may feel guilty or distressed by this. By discussing this possibility from the beginning you are setting the stage for them to express their feelings and ask their questions about results later, and it is an opportunity to reinforce that they did not do anything to cause a chromosome anomaly. Also, it will help them begin to understand the difficult concepts of incomplete penetrance and variable expressivity if these need to be discussed later.

Occasionally we will detect an anomaly that is unrelated to a child’s problems (such as 47,XXX in a child with multiple congenital anomalies) or an anomaly which confers a health risk that is not related to the reason for testing (such as deletion of a tumor suppressor gene that may lead to an increased risk for a tumor, often in adulthood). A brief mention of this possibility may be helpful.

Pretest Counseling

 


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