My grandpa had HD but my dad does not, am I at risk?
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Q. My grandpa had HD but my dad does not have it, am at at risk of getting HD.
Kyler, Young Adult, USA
A. Thank you for your question. I am sorry to hear that your grandpa had HD.
When someone with HD has a child, there would usually be a 50% (1 in 2) chance that the child would also carry the HD gene expansion, in which case we would expect them to develop symptoms of HD at some stage in their life. You may find the following HDYO article helpful, as it describes how the gene can be passed on in families in more detail. If your father did not inherit the HD gene expansion, you would not be at any increased risk of HD.
I was a little unsure from your question, when you say your father does not have it, whether you mean he has had a genetic test that confirms he has not inherited the HD gene expansion, or if you mean he does not have symptoms of HD.
This is quite important, as the age at which someone who carries the HD gene expansion starts to have symptoms can be very variable, so someone who does not have symptoms could potentially still carry the gene expansion. The average age to start with symptoms is around 35-50, but some individuals with HD have symptoms earlier or later in life than this. The longer someone lives without developing symptoms, the less likely they are to carry the HD gene expansion, so even if your father has not had a genetic test, the fact he is well is still likely to reduce the chance that he (or you) carries the HD gene expansion, although this will depend on how old he is.
Your local Genetic service would be able to provide more information if you wish. If so, the following website may help you to find your local Genetics service.
I hope this answers your question, and please do not hesitate to get back to us if you have any further queries.