Clinical Trial to Assess Influence of MyCyFAPP Use on GI Related QOL in Children With Cystic Fibrosis

Inclusion Criteria: 1. Diagnosis of CF as evidenced by one or more clinical feature consistent with the CF phenotype or positive CF newborn screen AND one or more of the following criteria: 1. A documented sweat chloride ≥ 60 mEq/L by quantitative pilocarpine iontophoresis (QPIT) 2. A documented genotype with two disease-causing mutations in the CFTR gene 2. Having pancreatic insufficiency (stool elastase \< 200 mcg/g stool) and using PERT 3. Age ≥ 24 months and \< 18 years at screening visit 4. Informed consent by parent or legal guardian; assent for children from age 12 years on 6\. Inclusion visit coincides with scheduled routine clinic visit 7. Ability and willingness to comply with APP use and evaluations at time of routine clinic visits as judged by the site investigator 8. Availability of wifi connection at home so that connection to the internet is feasible at home at least weekly. Exclusion Criteria: 1. Acute infection associated with decreased appetite or fever at time of run-in visit 2. Acute abdominal pain necessitating an intervention at time of run-in visit 3. Physical findings that would compromise the safety of the participant or the quality of the study data as determined by site investigator 4. Investigational drug use within 30 days prior to run-in visit 5. Started with CFTR modulator treatment less than 3 months before start of run-in visit 6. Inability to use the APP due to patient specific factors such as language or learning difficulties