Anyone know about genetics? Tanum??

[macwoozy]

I'm not sure if anyone will know the answer to this but it's worth giving it a go.

I have a heart condition that although it is often passed on by a dominant gene, in my case it is sporadic and is caused by a mutation.

My question is if and when my ds develops it(which is a 50% chance) will he have the same mutation type as me, or can that further mutate? I ask because I'm concerned that although he's not showing any signs of the condition through echo ecg etc, he is showing symptoms and because of this is having further tests. In this particular condition there is a genetic type that doesn't show anything structually wrong with the heart, so doesn't show up on ecgs or echos, but still carries the same potentially fatal complications. So, basically I'm worried that I will pass down my faulty gene that could further mutate into the type I've described.

As you can see I have no understanding of genetics, but would love to know the answer to this, so I can either be prepared, or have my mind put at rest.

It is my understanding of these things (and I'm willing to be corrected) that any mutation resulting in a condition such as yours would happen during the coming together of the egg and sperm cells rather than at some random point in a person's life. Therefore any mutation your ds has, whether it is inherited from you or arrived at by any other means, is "set" for life so any genetic testing he has had will remain valid - ie there will be no further mutations. Your own mutation will have happened at that very early stage rather than at some point during your life.

As I say, I may be wrong, I did several genetics modules as part of my degree but that was a long time ago now!

Has he had any genetic testing?

Hopefully someone will be along soon to clarify.

Many genetic conditions have something called variable penetrance which means that the same gene mutation can have different amounts of effect. Could this be the case with your son? It would be incredibly unlucky for your son to have a different mutation causing a similar disease which is what would probably have to happen to cause what you are describing. Without knowing the conditions you are describing it is difficult to be any more clear than this but I hope this helps.

Thanks for your replies Tiger and fleximum.

He has had no gentic testing, so it's just a matter of waiting to see if he does actually develop it over time.

It's hypertrophic cardiomyopathy. So is it right then that the chances of ds having a mutation of my mutation(oh 'eck I told you I am totally clueless about this[shame])very unlikely?

A mutation on top of your mutation is very unlikely, yes. Unfortunately it may well be as you say and you just have to wait and see. I'm glad they are taking any symptoms he is having seriously though as it could be something unrelated and fixable.

Is there a test for your particular mutation? If so it may be worth pressing to get him tested (or would you rather not know? completely understandable if that's the case).

The symptoms that he is showing - could they be caused by anything else?

If youe son has the defective gene from you, it will exist in the form that he ingerited from you in all his cells.

It is impossible for evey cell in your sons body to mutate in to the more dangerous form, all at the same time. Your son has billions of cells and they all carry the original (possibly defective) hopy of the gene. A second mutation would only happen in one of his cells.

The only way that the condition could get worse would be for his offspring if a muatation happened in the celss in his testes.

The symptoms could be related to something else, he has SN's so it is hard for him to describe what he truly experiences, but it sounds like pre-syncope and chest pain. I will ask about genetic testing though, although I haven't even been offered it.

Martianbishop, that is so good to hear. I've been so concerned that he's developed the type I decribed in the OP, although I still can't make sense of why they are repeating tests and an added holter test when he's showing no signs of heart trouble with regards to the tests that have already been performed.

Thank you all for helping me

There could have been a mutation when it passed from you to him, but that risk would be the same as for anyone else IYSWIM. and he would already have that muauation at birth

We can all pass on a spontaneous mutation,(if a cell in our perproductive cells mutates) but there is a general background rate of this.

Once you have a gene, it is in all your cells. Mutations happen in single cells, not all the cells at the same time.

Your son's DNA could mutate and he could pass a different version of the gene onto his offspring, but the gene he has at birth is the gene that he's got IYSWIM

Thanks for making this clear to me, too much googling for me I think, I start looking at so many possible scenarios, but thanks I can now accept that what I feared cannot happen, well not to get the type I decribed in the OP anyway. Thanks

Right, off to google some more

Have you had genetic counselling? If not, ask for a referal from your gp, all the regional genetic centres will have nurse and doctor genetic specialists who will be able to explain in a way that is clear for you.
hth

whitetulips Even though I'd like to have more children I'm not prepared to go through all this worry again. He has autism too, and looking at our family history that's likely to be hereditary too. Otherwise yes I do think I would ask for genetic counselling.