If I understand the original poster correctly, she has all the symptoms of cf (severe lung disease, digestive issues, etc) but has NEVER been tested in any fashion (sweat or dna). However, she does have two children with CF,both with 2 copies of DF508. Since we know that the children's father is a carrier of the DF508 and she herself carries at least one copy of the DF508, her question is ASSUMING she DOES have CF and has two DIFFERENT mutations, what is the likelihood that both boys would have the same mutations. She is assuming that they would have different mutations.
To the original poster. First off, may I ask why you're asking this question? Am I incorrect in my assumption that you've never had genetic testing? Have you had a basic panel that showed only one DF508 mutation, hence your question? Or, are you just assuming that you aren't double DF508 since you haven't been diagnosed previously?
Either way, here's your answer. If you do NOT have cf, the genetics that Julie stated would apply. However, if you have CF and have TWO copies of DF508 than each of your children would have 50% chance of having 2 copies of DF508 because each child would ALWAYS receive ONE copy from you and have a 50% chance of receiving no mutations from their carrier father or a 50% chance of receiving a second copy of DF508 from you.
However, IF you have CF but have ONE copy of DF508 and one copy of another gene, then each of your children would have a 50% chance of receiving DF508 from you and a 50% chance from receiving the other mutation (for sake of argument, we'll call it mutation X). The probabilities of genetics for each child would be as follows: 50% chance of receiving a "healthy" gene from father, 50% chance of receiving a DF508 from father, 50% chance of DF508 from you, 50% chance of X from you. THis translates into these probabilities for EACH child
25% chance the child will be a carrier of X mutation ONLY
25% chance the child will be a carrier of DF508 ONLY
25% chance the child will have CF with 2 copies of DF508
25% chance the child will have CF with 1 copy of DF508 and 1 copy of X mutation.
Now, for my personal opinion. Get the sweat test. If it's high normal (high 30s-40) or borderline (40-60), request genetic testing through AMBRY. I would do this regardless of whether you had a genetic test previously and ESPECIALLY if you've NEVER had a genetic test or had a genetic test other than AMBRY. Only AMBRY tests the full DNA strand and is capable of picking up rare mutations. Also, if you've never had ANY CF testing, I wouldn't assume that you couldn't have 2 copies of DF508. I understand that it's scary to find out, but as the previous posters have stated, it's far better to get the treatment you need so you can live as healthy and long of a life as possible. Especially for your children.
Please let us know what you find out. Good luck and God Bless.