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Will I have more repeats than my mother?

May 28, 2015

Huntington's Disease Youth Organization

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Will I have more repeats than my mother?

Q. My mother has HD and her genetic test shows 40 repeats. If I’ll have the condition, can I have more repeats than she has or will it be the same?

Fernanda, Young Adult, Brazil

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A. Dear Fernanda,

Many thanks for your question.

Although the number of ‘CAG’ repeats in the HD gene can sometimes change from generation to generation, this is relatively uncommon, and research has also shown that it is very unlikely to happen if the HD expansion is passed from a mother to a child, rather than from a father to a child. Therefore, if you were to inherit the expansion from your mother, it would almost certainly be the same size as hers (although, because it is technically quite difficult to measure the exact number of CAG repeats, the laboratory are usually only to define it to around +/- 1 repeats at that size).

I hope this makes sense, and helps to answer your question. If you have any further queries, please do not hesitate to get back in touch.

Best wishes