Does the specific defected gene have anything to do with it, at least, initially?
I know the ONLY problem I had was my digestion. I wasn't brought up doing b/t's AT ALL. I think I was in my 20's before I had my first lung infection, and in my 30's when I had my first I.V.
However, BECAUSE I wasn't doing b/t's as standard procedure (because I was naive and thought I would never be the typical CFer), I got sick big time. I laid in bed thinking I only had the flu...and because of waiting to treat with antibiotics, I damaged my lungs, causing me to have to retire from work (at the age of 35/36). Although I'm probably still considered mild to moderate, but my FEV1 is 39%, o2 is 94%.
Had I been doing b/t's everyday, my guess is that I would still be considered very mild. But that's just a guess, since no one knows how many days they are alloted, with or without CF.
I still think the genes determine what stage <i>we are born at </i>with CF. I had a baby brother who had lots of lung trouble and died at 18 months. ..and here I am at 40.