Asked By Ross, 38
The answer to this question depends, to some degree, on who was the gene positive parent. That is, the answer will be a little complicated.
If Ross inherits the gene (a 50% or 1 in 2 chance) then most likely he will have the same or very similar repeat count as his sister.
However, if inheritance is from the father, there is a small chance the repeat number will increase whereas this is less likely if inheritance is from the mother.
It is also important to remember that if the repeat number is less than 40 then the average age of onset of symptoms will be greater than if the repeat count was 40 or more. There will also be a less than 100% chance of developing symptoms of HD
-Dr Andrew




