I'm 31, fit and healthy - am I still at risk?
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Q. Hi, my mother, grandmother and uncles had HD. I’m 31 years old now, I’m very healthy and active, both physically and intellectually. I would like to know if I’m still at risk for HD? I have two children, one is 5 years old and the other is 3 months old. If I don’t have the gene mutation, they will not have it either? Two years ago I did several exams, I did a brain scan, and it didn’t find any lesion. Can I be at ease with this?
Pamela, Young Adult, Brazil
A. Dear Pamela,
Thank you for your email. I was very sorry to hear that your mother, grandmother and uncles had HD. To answer your main question, about your risk of HD, this will depend on which copy of the HD gene you inherited from your mother. We all carry two copies of the HD gene (whether we have a family history of HD or not), and symptoms of HD are caused when someone has one copy of the gene which is larger than usual (called a CAG expansion). When that person has a child, there is an equal chance which HD gene is passed on. Therefore, when you were born we would expect that there would have been a 50% (1 in 2) chance that you inherited the HD gene expansion.
It is great to hear that you are very healthy and active, and that you had a normal brain scan a few years ago. However, as the age at which symptoms of HD start can be very variable, unfortunately this will not necessarily mean that you did not inherit the HD gene expansion. A genetic blood test is available that could confirm whether or not you did inherit it, although before having this type of test it is important to consider the pros and cons of knowing this information. You may find the following HDYO article helpful, as it describes how the gene can be passed on in detail, as well as more information about being at risk.
In terms of your children, you are absolutely right that if you do not carry the HD gene expansion, they will not be at any increased risk of HD. On the other hand, if you do carry it they would each have a 50% chance. Even if they do carry it, it is likely that they would be very many years away from when the illness would affect them, and it is possible that better treatments will become available by then.
Many people at risk of HD find it helpful to see a genetic counsellor or doctor, as they could give more information about HD, as well as helping to address any difficult emotions that individuals at risk may be feeling. The Brazilian Huntington’s Disease Association may help you identify local genetics services in Brazil. I hope this is helpful, and please do not hesitate to get back to us if you have any further questions.