There is a large spectrum of abnormalities in the CFTR gene that leads to a partial function of the chloride channel and, thereby, an uncommon presentation of the disease, the “CFTR-related diseases”. This report aims to present a case of a patient with a single gene mutation related to cystic fibrosis, with an unusual clinical presentation among CFTR related diseases - chronic intestinal constipation. This patient is not a cystic fibrosis patient because he does not fulfil the disease’s classic criteria. Furthermore, since the mutation found is not yet described in the literature, it could be related to CFTR-related disease.