Welcome to our new Q&A series! We recently asked the community to submit their questions on genetic testing and Clare Gibbons, North York General Hospital Genetic Counsellor, has provided the answers below.
The Huntington Society of Canada would like to thank Clare Gibbons (left) for participating in the first round of Q&A and providing such important information for the HD community.
Q: Could you give advice regarding genetic testing and IVF? I know that there are tests that can be done once pregnant but in the UK that means termination if a positive test and for me I don’t want to have to go through that. Is IVF an option? Do you have any advice on finding information or support with this?
A: The testing that is done when a woman is already pregnant is called prenatal testing and would be done through either chorionic villus sampling or amniocentesis. With prenatal testing if a pregnancy has inherited the DNA expansion that causes HD then the only way to avoid having a child who inherited HD is to have a termination of pregnancy. If someone does not want to be in that situation, it is also possible to do preimplantation genetic diagnosis (PGD or PGT). The woman would undergo IVF so her eggs would be retrieved and fertilized. When the fertilized eggs grow to a certain stage of development, they can be tested to determine if they have inherited HD. Only embryos that are found not to have inherited HD would be transferred back to the woman’s uterus. There are a few things to consider with this procedure: one is the cost. IVF and PGD is very expensive. The cost may vary among clinics as well as countries or provinces. Some countries/provinces may cover some of the costs. Each person should check with their local genetics clinic or fertility clinic to find out specific details about cost. Another thing to consider is there is not necessarily a successful pregnancy after each procedure. Often, women have to go through a number of IVF cycles and PGD to get pregnant.
Q: What is the difference between predictive testing and genetic testing?
A: Genetic testing refers to any test of our genetic material, i.e. DNA. Predictive testing is a specific category of genetic testing that is done on someone who is at risk for a genetic disease but does not have symptoms of the disease. So if someone wants to know if they could develop HD in the future but currently has no signs of HD, that would be predictive testing for HD.
Q: Who do I contact if I want to go through predictive testing?
A: It depends on where you live. Most predictive testing is done through a genetics clinic that offers genetic counselling. You can contact your local genetics clinic to find out if they do HD genetic counselling and if they require a family doctor’s referral or if you can make a self-referral. Most HD organizations have links on their websites that help people find genetics clinics that provide genetic counselling for HD. You can also contact your local HSC Family Services team members, as they can also provide information on the local process and contact person at the local genetic clinic. Click here for a list of HSC Family Services team members near you.
Q: How long does it take once I decide to get tested?
A: That varies from place to place. There are different lengths in wait times for a genetic counselling appointments. Most genetics clinics require 2 or 3 in-person meetings and some require a neurology assessment or meeting with a psychiatrist. The important thing to remember is that these meetings and assessments are in place to support people through the predictive testing process. It is hard to know ahead of time if receiving HD results will adversely affect a person’s mood so genetics clinics prefer to provide as much support as possible everyone. It may be helpful to know that supports are also available before, during and after the predictive testing process through the HSC Family Services team as well. Click here for a list of HSC Family Services team members near you.
Q: Where do I get more information if I am thinking about predictive testing?
A: To get the specific information for your situation and process in your area, I would suggest an appointment at the nearest genetics clinic that has experience with predictive testing for HD. People can be seen in clinic just to talk about predictive testing, there is no commitment to going ahead with testing. You can also contact your local HSC Family Services team members, as they can also provide information on the nearest genetic clinic. Click here for a list of HSC Family Services team members near you.
Other resources Clare recommends that provide information on predictive testing: (click on the title to follow the link)
HSC Family Services Team Listing
HSC Genetic Testing and HD Fact Sheet
HSC Genetic Testing for HD Booklet
HDYO Genetic Testing Information
HDYO Genetic Testing Checklist
Canadian Coalition for Genetic Fairness (CCGF)