The study's main goal is to observe how effective elexacaftor-tezacaftor-ivacaftor is for improving the symptoms and signs of CF-related sinus disease.

To determine if elexacfator-tezacaftor-ivacaftor improves the signs and symptoms of CF-related sinus disease, before and after initiation of triple combination therapy, each subject will undergo sinus CT scan and complete questionnaires related to signs and symptoms of sinus disease.

Inclusion Criteria:

1. Subjects from 18 to 89 years old.
2. Subjects with cystic fibrosis and comorbid chronic sinus disease (historic diagnosis based on physician assessment of signs and symptoms and medical record).
3. Subjects who clinically elect to initiate elexacaftor-tezacaftor-ivacaftor therapy and/or that are ineligible for CFTR modulator therapy based on their genotype, but have class I/II mutations based on sweat chloride > 90 mmol/L.

Exclusion Criteria:

1. Subjects under the age of 18 or over the age of 89.
2. Subjects who do not elect to initiate elexacaftor-tezacaftor-ivacaftor for clinical reasons.
3. Subjects who had sinus surgery within the last 6 months or will have sinus surgery during the study period.
4. Subjects who have had a recent pulmonary exacerbation or viral infection within two weeks of initial visit.

People with cystic fibrosis and chronic sinusitis.