Yes there are a-typical cases, some people refer to it as "mild". I don't know how anyone can call a life threatening disease mild, but I guess they mean the symptoms are mild. My son's symptoms are mild at this time. He has rare mutations and does not have as many digestive problems as some people. His is mostly allergy and lung related. He has asthmatic tendencies also.
My son wasn't diagnosed until he was 15 because his symptoms were fairly mild. They did start to worsen and be more pronounced as he aged though. That is because CF is a progressive disease. Since Jordan's dx he has not had as many trips to the ER for breathing problems. That is because he is now getting the proper care. Before, we were reactive, not proactive, because we just didn't know any better.
Your siblings probably do have mild symptoms, but that doesn't mean they will always stay that way. I am certainly not an expert on CF, but I have been educating myself as best I can since my son's dx. Anyone I've spoken to about this disease has told me it's imperative to be proactive. This disease can sneak up on you and bite you in the butt so quickly. Jordan doesn't get sick often, but when he does, he gets really sick really fast! He looses weight so easily and it takes months for him to put it back on.
I know you are concerned about the kids. I would think that the clinic will request that they come in every three months. That seems to be the norm. I'm just glad they were seen by someone. Your perserverance has paid off.
Keep us posted.
Stacey