She is just being diagnosed later than normal if she actually has it. Cystic Fibrosis is a genetically inherited disease. This means you are BORN with the disease, you don't just develop it out of nowhere. It is part of your genetic make up, because you have an ion channel protein that is not working properly or not present at all. A person who does not have the two copies of the inherited recessive gene CANNOT have CF, but it could be another similar disease (similar symptoms) and diagnosis may take longer. The symptoms can vary with different individuals, just like anything else. Some have very mild symptoms where as other people have problems as soon as they are born, and great difficulties throughout adulthood.
Yes there is no given age except that they have seen it most in younger children.....
I can answer this because I am in health class. Yes you can develop cystic fibrosis at any age. It most occurs when you are young, sometimes you are born with it.
I am in high school and a girl in my class was recently diagnosed with cystic fibrosis