Specific aims:

1. To elucidate the biological mechanism that leads to pulmonary and nutritional improvement in CF patients following treatment with ivacaftor using advanced techniques to assess changes of the pulmonary and nutritional status
2. To examine the relation between the individual response to ivacaftor and the presence of modifier genes associated with CF disease severity,
3. To assess altered CFTR function using new available in vivo tests,
4. To validate newly developed in vivo sweat tests with well established functional tests,
5. To establish correlation between the CFTR response to Vx-770 measured in a new ex vivo method (organoids) and the actual clinical and/or functional response in individual patients,
6. To examine response in other CF-specific features such as aqua wrinkling.
7. To examine if sleep/activity level changes.
8. To establish a biorepository to enable further investigations.

Inclusion Criteria:

• any patient being prescribed ivacaftor

Exclusion Criteria:

• only relates to specific tests

CF patients with any of the following mutations G551D, G178R, S549N, S549R, G551S, G1244E, S1251N, S1255P, G1349D and G970R approved by Health Canada to receive ivacaftor.