To ask an embarrassingly simple maths question?

[NappinginaMosesBasket]

I don't know why I can't get my head round this!

If DH has a 50/50 chance of having inherited a gene mutation, and if he does our DD has a 50/50 chance of inheriting it from him...

Does that mean (while we're awaiting his results) she currently has a 50/50 chance of having it because there's as much chance he has as hasn't and in turn the same odds for her, OR a 25% chance because there's 50% chance if he has but 0% if he hasn't?!

It's autosomal dominant, doesn't affect me and doesn't skip generations

Don't know why I can't figure this one out but I know ultimately it's pointless wondering and we will have to wait and see

[UtterlyUnimaginativeUsername]

26%.

[Dontstepinthecowpat]

Oh I have no idea but two of my kids inherited their DH 50/50 autosomal dominant genetic condition, one didn’t and the other hasn’t been tested yet so if he is also clear then it will be 50/50 split.

[Dontstepinthecowpat]

Their DF, my DH

[PenguinPandas]

25%

[TigerQuoll]

Maybe easier to visualise as coin flips?

If tails is inheriting the mutation and heads is not.

It is the chance of getting 2 tails from 2 coin flips.

HH | HT | TH | TT => 1/4 or 25%

[roundthehorn]

I have an autosomal dominant condition and there is a 50% chance of passing it on with each pregnantcy (I have 2 without and one with). If your partner has the mutation then there is a 50% chance he'll pass it on, if he doesn't there is a zero chance.
If your partner's result comes back negative then there is no need to test your child.

[IfyouseeRitaMoreno]

Unfortunately roundthehorn is right. It is 50% because you only need one copy of the gene for it to manifest. It’s not like recessive where you need two.

To quote:
There are many genetic conditions where if one gene of the pair is not working, the other one cannot make up for it and it can cause a genetic disease. This illustrates a common pattern of heredity called autosomal dominant inheritance.

[CosmicComet]

She currently has 25% chance. But that will change when you get DH’s results. At that point she’ll either have 50% chance if he has it or 0% chance if he doesn’t.

[IfyouseeRitaMoreno]

sorry, to clarify, my post is only true is your DH actually has it.
Good luck.

[NappinginaMosesBasket]

Thank you everyone, sounds like the "current" chance is 25%

I understand that actually it's either 50% or 0% depending on whether or not he has inherited but it feels better to know that it sort of sounds less likely overall... if that makes sense