The Neurodevelopmental Disorders Diagnostic Clinic at CHEO
Information for Families
Why is my child being seen by a Geneticist?
Your child has been referred to CHEO for an assessment by a Geneticist in the Neurodevelopmental Disorders Diagnostic Clinic (NDDC). A Geneticist is a medical doctor with expertise in genetic testing. You may also meet with a genetic counsellor, who is a medical professional specializing in explaining genetic information. Some common examples of neurodevelopmental disorders include autism spectrum disorder (ASD), global developmental delay (GDD), speech or language disorder and intellectual disability. If there is no obvious cause for a neurodevelopmental disorder in a person, genetic testing is one way to try to find the cause.
What will happen during the visit?
You will be asked questions about the pregnancy, birth, and health of your child, and your child’s family history (on both the mother and father’s side). The doctor will do a physical examination of your child, so make sure he or she is wearing clothes that can be easily removed.
The doctor or genetic counsellor may offer genetic testing for your child, depending on what has already been done and what information he or she gets from the visit. Genetic testing is usually done by a blood test. There is no obligation to have genetic testing – the doctor or genetic counsellor will help you decide if it’s the right choice for you and your child/family. Parents may also need to give a blood sample, depending on the type of genetic testing offered, so be sure to bring a valid health card.
What types of genetic tests may be offered?
Chromosomal microarray: this test looks for extra or missing pieces of chromosomes. Chromosomes are the structures that contain our genetic material (genes). About 10-20% of people with a neurodevelopmental disorder have a chromosome imbalance that can be found with this test.
Testing for Fragile X syndrome: this test looks for the specific type of genetic change (or mutation) on the X chromosome that causes Fragile X syndrome.
Biochemical testing: this test looks at the levels of certain products in the blood and urine to see if they are too high or too low. Some patterns may mean that there is a genetic condition causing a problem with the body’s metabolism.
Testing for a specific genetic syndrome: the Geneticist may determine that a specific genetic condition (or syndrome) should be ruled out. There are thousands of genetic syndromes, each caused by a spelling mistake in a specific gene. A different type of genetic test is needed for each syndrome or group of conditions.
Why should I consider genetic testing for my child?
Genetic testing has one goal: to find a specific cause of your child’s neurodevelopmental disorder. There are many reasons you may find it helpful to have this knowledge:
Recurrence risk: Some families want to understand what their chances are of having another child with the same or similar neurodevelopmental disorder as their child. Only a genetic assessment with genetic testing can answer this question. Some types of genetic conditions are inherited, even if there is no family history.
Treatment options: Knowing your child’s genetic diagnosis may help doctors determine which medications to use or avoid, what types of illnesses they are at increased risk for, and whether there are research studies your family can benefit from.
Support: Although most genetic conditions are relatively rare, many conditions have online networks where parents can share their experiences, get advice and find out about the newest research.
Even with our most advanced technologies, genetic testing doesn’t always find a cause for a child’s neurodevelopmental disorder. In those cases it might be worth seeing a Geneticist again in a few years’ time to see if more testing is available.