CFTR and cystic fibrosis: First, clinical observations and comparison of disease phenotypes in CFTR2 and CFTR-France databases suggest an incomplete penetrance of CF for variants that have been classified as CF-causing in CFTR2 but milder in CFTR-France, such as c.328G>C (D110H), c.349C>T (R117C) or c.617T>G (L206W).