CHANCES TO GET ALS

QuiQui

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Hi! I have ALS family history. I know that my grandfather died from ALS in the age of 51. Then his daughter (my mom) died from FTD in the age of 48, her sister is healthy. Now I am 40, and I have a sister, 31 y.o. I have read tons of material about it. I know that this can pass down the family line 50%. But it's just a theory. In my research of examples of ALS manifestations in 3 family generations, I have not seen a generation where ALS would not have manifested. If it's 2 kids, at least one (very often both) got sick. If it's 3 kids, of course 2 were sick. It's like it doesn't skip. Also I noticed that in all examples elder kid got sick. All this is telling me that actual probability is much higher than 50%, I just have a feeling sometimes that I am doomed. Does anyone know a genetic aspect of ALS. I would appreciate if you share your knowledge. Thank you.
 

Nikki J

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It is Mendelian genetics It is not a theory it is science. and yes if there is a genetic mutation in a parent there is a fifty percent that any one child will inherit it and an equal chance they will not. The probability is always 50/50 but it does not mean any given family will be 50-50. Some are lucky some are not Just like flipping a coin. You might get 5 heads a row but over time it will even out If a person does not inherit a mutation they can not pass it on so it would stop in that branch of the family. You won’t see skipping generations in the mutations that are what they call highly penetrant because the carriers virtually always get the disease.
 

QuiQui

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Hi, thank yoг for your response. This is where I am confused. Isn't it that if my mother hasn't passed the defected gene to me and my sister, it will be considered "skipped"?
 

Nikki J

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generally skipped would describe a situation where a grandparent was affected then there was a healthy parent then an affected child but certainly whatever you call it it is perfectly possible that neither you nor your sister inherited the family mutation and it ended in your branch of the family. If that happened it won’t pop up again so more ended than skipped because you can not pass on a genetic trait to your offspring that you do not have
 

QuiQui

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I just want to say thank you for your work here. I noticed you answer a lot of questions (I am sure a lot of the same questions) over and over, trying to cheer up people in panic and desperation. 🙏
 

QuiQui

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So do you mean that even in families with 5 kids ALL may be healthy? That is every healthy kid born does not raise chances to get ALS for every subsequently born child?
 

Nikki J

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Each person has a 50/50 chance. Certainly it is possible to have all unaffected children if you are lucky. The reverse is true too. My mother was one of 5 and 5 were affected. Somewhere your hypothetical 5 healthy offspring probably exist balancing us out.
 

QuiQui

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That's the thing. I only hear bad stories about proportion in FALS. Like a bunch of them. Always more affected than not. No one comes and says. Oh, I had 5 sibs and just one was affected. That's why I don't understand why it's scientifically 50/50 while actually in real life it sounds like it's 80/20.
 

Nikki J

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Because the affected people are the ones talking about it and joining groups etc. my grandfather was one of 8 -2 were affected.6 were fine I don’t think the people who are grandchildren of the healthy ones give this much thought at all
 

QuiQui

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Then these 2 would tell us that it was only them out of 8 and we would think, ok, 6 are unaffected, that's great. But instead we only here about proportions not in our favor. Well, sorry, I am just trying to find a glimpse of hope but probably overthinking. I guess, if I don't want to get tested, I have no other choice than to learn how to live with 50/50 and have faith.
 

QuiQui

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On the website of the ALS Association website it says:

"A child born to someone with FALS has a 50% chance of inheriting the FALS gene mutation".

Followed by:

"Typically, there will be someone in each generation with ALS and/or dementia".

Aren't these two statements contradict each other? The first one states 50% probability which is what we were talking about here. But the second one literally states that it's almost 100% that someone in the same generation will have it.
 

Nikki J

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Once no one happens to inherit a mutation it is the end for that line so when someone ( like me) shows up in the neurologist’s office and they take the family history they see a parent and a grandparent etc. if my mother hadn’t inherited the mutation I would never have had a neurologist visit.

also statistically in larger families someone is probably going to lose that 50/50 in each generation. It isn’t guaranteed but it is likely. However I think that statement was made referring to the FALS patient arriving in clinic
 
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