Scare

As some of you know, one of my nieces has cystic fibrosis.
That means that twice or three times a day, she has to stop what she is doing, and do 30 minutes to an hour of physio and clapping. She has to take pills(enzyme) for pretty much anything she eats.
That means that she have to stop being a child for that time...Even if she is doing great, being in shape and energitic and all, she still hate that she have to stop doing stuff, like playing to do her physio. It have mature up too much for a child. She would say to you that she needs her pills to eat, or even refuse to eat some stuff, because she doesn't want to take them!
As much as I love her, and the fact that I always wanted children, I'm afraid that when I would get pregnant, my child might have it too(not like I'm gonna pregnant anytime soon)! She does live a pretty normal life, but I hate it to see her put a pause on her life. She is not even 6, and she has to sometime act like an adult...
And even if the life esparancy is going up each year with the new medication on market, it is still only 39 for now. I might see her or my future children die... That, I don't want to at all.
I know that a DNA profiling test to find out if i have the gene that cause it will clear my mind of it, but I'm afraid to take it. If I actually have it? Would I be afraid to have kid all the rest of my life because of that?