Questions about Familial ALS

[schaper8]

We have known for a while now that my mother's family has familial ALS. We know that ours is not caused by the SOD1 gene mutation, so the exact cause is unknown, as it is for the majority of ALS patients.

My grandfather very likely had FTD and he has a brother who died of ALS and six of that brother's children died from or have ALS. These appear to be the only 2 out of six children in my grandfather's family that had the gene. My grandfather had 8 children- 2 of those children have died from ALS (one of whom had FTD prior to showing ALS symptoms), it is also very likely that another also died from ALS. My mother is 73 and has had several serious health issues that would have probably triggered ALS by now. Two other brothers show no signs of ALS. The oldest sibling of the 8 offspring died a few years back from cancer- now his oldest son is showing symptoms of ALS and is being tested for this and other neurological diseases.

I kind of freaked out when I heard about his symptoms, as it has always been my understanding that ALS is a dominent gene disease and that a parent had to pass the gene to a child. Is anyone aware of strains of familial ALS where this is not the case- that it could occur randomly within the hereditary blood line- or is the more likely scenario that this uncle died of cancer before his ALS symptoms appeared? I have asked one of this uncle's children if he was showing symptoms of FTD prior to dying of cancer- if the answer is yes, then I would be able to connect the dots and quit worrying if I, or my sisters, could be at risk of developing ALS without my mother having it...

[asantiago]

Reading comprehension has never been my strong suit so forgive me if I am misinterpreting... Are you asking if it's possible for ALS to skip a generation? If that is your question then the answer is yes. My mother died from ALS though her mother never developed the disease, it came from her mother's mother, my mother's grandmother.

We thought the disease had died out in a sense but it reappeared suddenly about a year ago. You can be passed the gene that carriers the ALS but not develop symptoms of the disease thus being able to pass it to your children without having the disease yourself.

[schaper8]

My question was a bit meandering... I understand from your answer that if my mother has the gene (or gene mutation), but doesn't develop ALS, one of her children can. If my mother doesn't have the gene though, has anyone seen this gene show up randomly in the family tree, ie. uncle had ALS, but parent didn't, then a neice develops ALS? (as I mentioned, I think that if she had the gene or mutation, it would have been triggered by several surgeries and illnesses she has had over the last several years)