I'm searching for information on HD because my grandfather passed away from HD. My mother and I have talked a lot about the onset of HD in her family line. This brings on great concern for me, my sister, and my mother because we're not exactly sure about the genetic process required to pass the gene. I understand that my mother has a %50 chance of developing the disease but, is it possible that she could pass the gene without developing symptoms? And if so, what is the chance that me and my sister could develop HD? And is there any significant risk to the different sexes (i.e. is there a greater chance for a male to pass it or a female) and how do I educate my fiancee more... she's Japanese and I cant seem to find too much information for her. If anyone can help please send me an e-mail or you can ICQ me 81697737. Thank you

Dustin

In Memory of
Charles Schleider (my Grandfather)

Dustin

HD is a dominant gene (not recessive) so your mother will have 50% risk and you and your sister will be at 25% risk.

Males and females pass on the gene with equal probability.

I have heard anecdotale evidence that the gene may occasionally be passed on without developing symptoms, but I believe (I am not an expert!) that this is due to the person not reaching the age of onset. Age of onset is thought to be linked to the number of 'DNA repeats' in the person's Huntington's gene (sufferers of Juvenile HD always have a high number of repeats) but studies are ongoing in this area.

There is a test available which can tell your mother with great accuracy whether or not she has inherited the gene. The decision to take it should only be made with prior counselling and a lot of thought. Not everyone wants to know their status. You or your sister could also take the test but you would have to consider how you would keep information of a bad result from your mother, if she does not want to know her own status - the gene is not known to skip generations.

Best

Chris Barker
Vice Chair
Huntington's Disease Association - Dorset Branch (UK)

Dustin

Me again.

For your fiancee try:

[homepage1.nifty.com]

There is no 'www' prefix.

This should get you in to the Japanese site (you can select the Japanese language once you're in).

Hope this helps.

Chris

I believe you have been given misinformation. Because HD is dominant, it cannot be be carried without symptoms or simply passed on to the following generation. You either have it or you do not have it. there is no 25%. If my parent does not have the gene, I can not have it. If I do have the gene, I do have huntingtion's. If my parent has it, but I do not, then my children are at no risk. However, Chris is right that the symptoms MAY come on later in life. My father in law was able to continue working until he was 65 with few symptoms. He developed his symptoms quickly then, until he was bed ridden. He lived till he was in his late 70's.
Hope this is helpful.
Linda

To clarify:

Linda is correct inasmuchas you either have the HD gene or you don't. The only way it would *appear* to skip a generation would be if someone with the gene died before onset from some other cause e.g., but rarely, old age.

In terms of probability, the chance of the offspring of a gene-carrier (in this case your grandfather) inheriting the gene is 50%, hence your mother as his offspring is at 50% risk.

As you are a further generation away from your grandfather, the probabilty of you inheriting the gene is 50% times 50%, i.e. 25%.

(If your mother were to test positive for the gene then you as the offspring of a gene-carrier would then be at 50% risk.)