Can a child have HD if their parents are over 50 without symptoms
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Q. Hi there i wanted to know, since HD is a autosomal dominant gene. Can one (an offspring) have it without parents having any symptoms they have HD when they are both well into their 50’s?
Michelle, Young Adult, USA
A. Hi Michelle,
Many thanks for your question. You are quite correct that HD is an ‘autosomal dominant’ condition, and this means that if someone has a parent who has the HD gene, there would usually be a 50:50 chance that they would have inherited it. However, the age at which symptoms of HD begin is very variable (the average is around 35-50, but can affect some people earlier or later in life). For someone who started out at 50:50 chance of inheriting the HD gene, the longer the person lives without symptoms, the less likely it is that they did inherit it, although unless someone has had a genetic test it can never be ruled out completely.
I wasn’t quite sure from your question whether you were asking whether it is possible to get symptoms of HD with no family history of the condition? Most people with HD have inherited the HD gene from a parent who also has it (following the autosomal dominant pattern as above). However, in rare cases the gene change that causes HD happens for the first time in an individual, in which case there would not necessarily be a family history of HD in their parents/extended family.
I hope this helps answer your question, but please get back in touch if you have any further queries.