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Can you be a carrier without any symptoms?

October 25, 2016

Huntington's Disease Youth Organization

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Can you be a carrier without any symptoms?

Q. Is it possible to carry the HD gene but never show any symptoms?

Lewis, Young Adult, Australia

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A. Hi Lewis,

Many thanks for your question. If someone has a ‘full expansion’ of the HD gene, they would be expected to develop symptoms of HD at some stage in their life. The average age at onset of symptoms is around 35-50, but a minority of individuals do develop symptoms later (or earlier) in life than this. So, a small number of people with the HD gene may not have any symptoms until quite late in life.

In addition, some people have a smaller (intermediate) expansion of the HD gene. Individuals who have a gene in the ‘reduced penetrance’ range (36-39 CAG repeats) often do not develop symptoms of HD at all, or may develop them only in old age. You can find more information about the different size HD genes in this HDYO article.

I hope this helps answer your question Lewis, but if you have any queries please do not hesitate to get back to us.

Best wishes