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My dad is 77 - can he still get HD?

September 26, 2015

Huntington's Disease Youth Organization

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My dad is 77 - can he still get HD?

Q. My grandmother had HD and died aged 75. My Dad is much older than my mother and is now 77 but has no signs of HD. Does this mean that it’s unlikely that he won’t get it and therefore I won’t either?

Sandra, Teen, UK

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A. Hi Sandra,

Thanks for your question. Yes, you’re right, it does look very unlikely that your dad will get HD himself if he is well at the age of 77 years. If your dad has not inherited the gene fault responsible for HD then you will not get it either.

The only remaining small possibility relates to whether your grandmother could have had a CAG repeat size in the reduced penetrance range (36-39 repeats). You may already be aware that HD is caused by a CAG repeat expansion. This HDYO article helps to explain CAG repeat size. Not everyone who inherits an HD gene in the reduced penetrance range will develop symptoms, or if they do onset is usually later in life. If your grandmother had an HD gene in the reduced penetrance range, there would be a 50% chance of passing it on to any children. Whilst this is a less likely scenario, you would be able to discuss your family history and options more fully at a genetics clinic (your GP can refer you). The genetic counsellor will usually begin by drawing up a family tree and ask about family members, ages they started with symptoms and whether anyone else in the family has been tested.

Best wishes,