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Cystic fibrosis transmembrane conductance regulator gene mutations in severe nasal polyposis
R M Irving1, R McMahon, R Clark
1Molecular Genetics Laboratory, Addenbrooke's Hospital, Cambridge, UK.
Insights
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene are linked to various conditions. This study found no significant association between CFTR mutations and isolated nasal polyposis in adults.
Area of Science:
- Genetics
- Pulmonology
- Otolaryngology
Background:
- Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause a spectrum of clinical conditions.
- Isolated features of cystic fibrosis, such as mild lung disease, pancreatic insufficiency, or male infertility, can occur with CFTR mutations.
- Nasal polyps are a known manifestation of cystic fibrosis, but their role as a sole presenting symptom is unclear.
Purpose of the Study:
- To investigate whether severe nasal polyposis, in the absence of other cystic fibrosis symptoms, is associated with mutations in the CFTR gene.
- To determine if CFTR gene mutations represent a monosymptomatic form of cystic fibrosis presenting solely as nasal polyps.
Main Methods:
- Genetic screening of the CFTR gene was performed on 55 patients with severe nasal polyposis.
- The screening focused on mutations commonly found in cystic fibrosis patients.
- Analysis included identifying carriers of known CFTR mutations.
Main Results:
- Three CFTR mutation carriers were identified among 55 patients with severe nasal polyposis.
- One patient carried the R117H mutation, and two carried the delta F508 mutation.
- The carrier frequency was not significantly higher than in the general population, suggesting CFTR mutations are not a common cause of isolated nasal polyposis.
Conclusions:
- The study found no significant association between CFTR gene mutations and isolated severe nasal polyposis.
- While a slight association cannot be entirely excluded, the vast majority of patients with nasal polyposis do not have CFTR gene inactivation.
- Nasal polyposis is unlikely to be a monosymptomatic presentation of cystic fibrosis due to CFTR gene mutations.
Abstract:
A wide range of clinical phenotypes are associated with mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. In some cases, CFTR mutations have been identified in adults presenting with isolated features of cystic fibrosis such as mild lung disease, pancreatic insufficiency or male infertility, with normal sweat duct function. Nasal polyps are also a prominent feature of cystic fibrosis but it is unknown whether they also may represent a monosymptomatic form of the disease. We have screened the CFTR gene of 55 patients with severe nasal polyposis, who had no other features which would suggest a diagnosis of cystic fibrosis. The screening looked for mutations common to 86% of sufferers from cystic fibrosis. Three carriers were detected including one patient with the uncommon R117H mutation and two carriers of the delta F508 mutation. In addition there was one presumed carrier with a cystic fibrosis child, whose mutation we did not detect. This study has identified three CFTR mutation carriers in 55 patients with severe nasal polyposis. This is not significantly higher than the incidence in the general population. We cannot, from these figures, categorically rule out a slight association between CFTR mutations and simple nasal polyposis. However, we have demonstrated that the vast majority of patients with polyposis do not have inactivation of the CFTR gene.