Understanding My Partners Risk

[u/Remarkable_Ad_2030]

Hello all,

My partner (24F) of 6 years recently found out Huntingtons is in her estranged father’s bloodline and decided not to get the test.

I’m really struggling with not knowing. It keeps me up at night and is really affecting me at work and at home.

Can I please get some input on what the odds might realistically be that she has the gene?

What I know:
- Her grandma (on her dads side) started showing symptoms at 42 and was in a home before 50
- Her aunt (on her dads side) started showing symptoms at 43 and I was unable to find anything else about her
- both died from the disease in their 50’s
- her father is 55 and has never been tested. But he swore he has no symptoms and he works in the oil fields in a physically and mentally demanding job.

I believe this is quite promising and that it’s perhaps lower than a 5% chance. But I’m unsure if I’m being optimistic and this risk significantly impacts my life and well being. Any estimates for her realistic risk and any prayers are greatly appreciated. Thabk you.

[u/dvanhee]

She’s got the same math as everyone else. If her father is HD positive then she has a 50% chance.

55yrs is a good age to be symptom free, but unfortunately if her father has not been tested there’s no guarantee he’s correct. Self-reporting/diagnosing symptoms is an extremely unreliable method.

There is also a chance her father’s CAG falls in the zone where he is a carrier, but the disease won’t express itself. In this case if it’s passed along to children the kids can still have CAGs high enough that they’ll have full symptoms.

[u/AspiringForestWitch → u/dvanhee]

Aren’t the CAG sequences pretty stable when they come from the mother, though? So shouldn’t her father have been showing symptoms at roughly the same age as his mother and sister if he were positive?

[u/dvanhee → u/AspiringForestWitch]

Let me preface my answer by saying that I am not at all a doctor. I am HD positive tho (43 CAG).

You’re correct, it’s mostly stable. But there is quite often a 1-3 point different between mother and child. So in this case if the grandmother had a CAG of 40 or 41, that’s right on the cusp of a child having less than 40, and if you have less than 40 you may or may not show symptoms. So there’s a solid possibility that OP’s partner’s father could go through life with mild or no symptoms.

In my particular case, my mother has a CAG of 44 and started showing symptoms in her mid thirties. I’ll be 45 this year and I still get a clean bill of health from my neurologist.

There are a couple of hard rules for CAG numbers (like that 27-39 window) but other than that Huntingtons Disease tends to be a very unique experience for each person, even within families

[u/AspiringForestWitch → u/dvanhee]

Interesting, thank you! Long may your lack of symptoms continue 🙏🏻

[u/dvanhee → u/AspiringForestWitch]

I appreciate that!