People with cystic fibrosis (CF) produce a lot of thick mucus in their lungs as a result of having two mutated copies of the CFTR gene. They frequently catch infections and some (6-18%) will develop allergic bronchopulmonary aspergillosis (ABPA), a chronic lung condition involving a hypersensitive response to Aspergillus fungus in the lungs. Symptoms of ABPA are variable and can include treatment-resistant asthma, collection of fluid in the lungs, or bronchiectasis.
It has been suggested that even people who are only carriers of CF (i.e. have one mutated copy and one normal copy) might also be more susceptible to ABPA. Being a carrier for CF variants is already known to be associated with asthma, COPD and impaired lung function.
A new study supporting the link with ABPA was recently published in the Journal of Asthma by authors at the National Aspergillosis Centre (NAC) in Manchester, with the help of the Manchester Centre for Genomic Medicine. Of 156 ABPA patients at the centre who underwent genomic screening, 18 (around 1 in 9, or 11.5%) were found to carry at least one mutated copy of the CFTR gene (most commonly variant ΔF508), which is much higher than the proportion in the general population (around 1 in 30, or 3.3%). Two of these patients (1.3%) had two mutated copies and went on to be diagnosed with CF.
Clinicians treating ABPA patients should keep in mind that a minority may have undiagnosed CF, or be carriers who might benefit from genetic counselling. Conversely, clinicians treating CF patients and their relatives should be mindful that their asthma could have a fungal component, in which case they may benefit from antifungal therapy.