Question on Passing Gene

[harvey]

1) For example, my grandson has the CF mutation 1717-G>A which
we assume probably came though my line.  Would this mean
that some of my siblings, and my son would have the same
1717-G>A?  Or could it be the 508 strain just as
easily?<br>
<br>
2) My grandson has both the 1717-G>A and the delta 508...so
which gene would he pass on? One of the two, both, or?<br>
<br>
3) Does anyone know if having two stage one genes (but different
ones) is better/worse than having two of the same kind? (like
double delta 508s).<br>
<br>
4) Is is generally better to have two different strains of CF than
two of the same?  Do they double in intensity or do they tend
to cancel each other out? Or just different parts of the body
affected?<br>
<br>
Thank you for taking time to share your knowledge/experience,<br>
<br>
Harvey<br>
I never took genetics in college but I do believe that
"knowledge is power."

 

[NoExcuses]

1. There's no way of knowing which gene your son gave to your grandson without genetic testing. It could be the 1717-G>A or it could be the Delta F508. And it's not necessarily you that gave your son the gene. I could have been your husband. You can be tested though to find out which gene and if in fact it was you who gave the gene to your son. If you do carry the gene, then yes, your siblings could carry the gene as well.

2. Yes, your son has both genes, this is why he has CF. Every human has 2 copies of every type of gene. So his sperm will carry either one CF gene or another. It just depends on which sperm fertilizes the egg.... it's a 50/50 chance to pass on each gene.

3. CF genes are pretty poor predictors of clinical outcomes. So much goes into it - compliance with meds, healthcare, modifier genes, environment.

4. Just to clarify - strains is a word used for bacteria. Mutations are used for genes. So like I said in #3, different or similar genetic mutations don't correlate well with cinical outcome. There is so much more than genetics that goes into how the patient fares. There is definitely not "canceling each other out".

Hope this helps! <img src="i/expressions/face-icon-small-smile.gif" border="0">

 

[julie]

Harvey,

Looks like Amy answered your questions for the most part but just wanted to clairify that in #2, she must have meant grandson vice son.

1. It's entirely possible that either mutation your grandson has, came from you OR your spouse and that one mutation was passed onto your son, which he then passed onto his son (your grandson). The only way to know if the mutation came from your, or from your spouse is if you had a genetic test. So, you may not even be the one who passed th mutation on, it may be your spouse.

If you are the one who carries the mutation, then YES, some, all or none of your siblings may also have the mutation. CF is a disease of "chance" in a pregnancy so there's no way to know without genetic testing.

And as Amy said, you or (or your spouse) could be a carrier of EITHER mutation. There's no process of elimination that would deduce which one came from "your side" of the family (vice your grandsons mother).

2. Your grandson will pass on one of the two mutations he carries if he has children, that is a given. But again, there is no way of knowing or even determining which one that will be. It could be that one of your grandsons children ends up as a carrier of the 1717-G>A mutation and the other ends up with the Delta F 508. Or all the children could end up with the 1717 mutation or all with the DF508 or any combination.

3. With Amy again on this one. My husband has double Delta F508. Supposedly he has two of the "worst" CF mutations and therefore assumably, should have a bad CF case. But, that's not the case at all for him. He's pretty healthy and does well. There is still so little known about mutations, but what they do know at this point is that mutations do NOT determine severity. There is research regarding "modifier genes" that have nothing to do with mutations, but that research has not been completed or concluded yet.

4. Same as above with this fourth question. Because it's now known that CF mutations do NOT determine severity or problems or anything of the sort. These things have been concluded because of studies of siblings in teh same families who have the same CF mutations, yet have very very different problems and complications associated with their CF. Don't weigh much of anything about yoru grandsons CF on his mutations. They aren't predictors of anything.