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How many of us will get HD?

October 13, 2011

Huntington's Disease Youth Organization

HDYO has more information about HD available for young people, parents and professionals on our site:


How many of us will get HD?

Q. “Me and my two brothers are all at risk. How many of us will get HD?” Sarah, 15, America

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A. Hi Sarah, Thank you very much for getting in touch via HDYO. I hope you have found the website and its content useful and supportive? With regards to your question I am basing my answer on you and your siblings being at 50% risk with either your mum or dad having HD, or the changed gene. The truth is that we just don’t know between you and your brothers who may develop HD. It is possible that none of you could develop HD, or that one, two or all three of you could have the changed gene. I often explain having, or not having, the HD gene as being like the flip of coin. Imagine heads is the HD gene and tails is the normal gene. You could flip the coin 3 times and it lands on heads every time thus meaning everyone will develop HD or it could be tails meaning no-one will develop HD or it could be a mixture of heads and tails meaning that some of you will have the gene and some of you won’t have the gene. Therefore no-one can say in any family how many people will have the gene, unless you undergo predictive testing when you reach the legal age to do so (18 in most countries), however this isn’t a decision to be taken lightly or rushed into.

You may wish to look at the HDYO sections on being at risk, the HD gene, What is HD and also Predictive Testing further information.

I hope this helps to clarify things

Kirsten Walker - HD Specialist Youth Worker