Inclusion Criteria:  The subject must have given their free and informed consent and signed the consent The subject must be affiliated or beneficiary of a health insurance plan Women and men are included The patient is at least 12 years old. The patient has cystic fibrosis or a CFTR pathology and therefore carries two mutations (with at least one mutation affecting splicing) in the CFTR gene. Patients who volunteer for rectal biopsy collection (only from Montpellier University Hospital) must be at least 18 years old.  Exclusion Criteria:  The subject is in a period of exclusion determined by a previous study. The subject is under judicial protection, under guardianship or under curatorship The subject does not accept to sign consent It turns out to be impossible to give informed information to the subject The subject does not read the French language fluently The subject is a pregnant or breastfeeding woman The subject has porphyria, or has hepatic insufficiency, or suffers from epilepsy, or suffers from conduction disorders, or suffers from severe heart failure, has a cons-indication to the use of a local anesthetic spray.  Specific non-inclusion criteria for rectal sampling:  the subject has thrombocytopenia the subject has a bleeding disorder The patient has severe inflammation of the rectum.