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I have two siblings, is it possible that none of us will get HD?

June 18, 2013

Huntington's Disease Youth Organization

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I have two siblings, is it possible that none of us will get HD?

Q. My mother has Huntington’s Disease and I have two other siblings. I was curious if there was a possibility that all of us would not develop the trait, or if at least one of us will end up with the disease because of the 1 out of every 2. Thank you.

Kellie, 18, USA

A. Hi Kellie,

Thanks for the interesting question. The answer is that your risk is totally separate from that of your siblings. In other words, if your mum has HD, then your risk of having the HD gene is 50% regardless of what happens to your siblings. This means that it’s possible that all of you, some of you, or none of you would have the gene.

At a very basic level, it’s like flipping a coin; usually you get a mix of heads and tails, but sometimes you get either all heads or all tails. However each flip is an independent 50:50 chance.

I’m sorry to use such a trivial example (flipping a coin) to talk about such a significant thing (HD), but it’s an accurate description of the statistics.

Best wishes


Kellie – to add to what Hugh has said, we actually have some information about this very subject in HDYO’s being at risk section - see the segment 50/50: Siblings - “One of us must have it”

Take care,

Matt, HDYO