Should diffuse bronchiectasis still be considered a CFTR-related disorder?

Although several comprehensive studies have evaluated the role of the CFTR gene in idiopathic diffuse bronchiectasis (DB), it remains controversial. We analyzed the whole coding region of the CFTR gene, its flanking regions and the promoter in 47 DB patients and 47 controls. Available information about demographic, spirometric, radiological and microbiological data for the DB patients was collected. Unclassified CFTR variants were in vitro functionally assessed. CFTR variants were identified in 24 DB patients and in 27 controls. DB variants were reclassified based on the results of in silico predictive analyses, in vitro functional assays and data from epidemiological and literature databases. Except for the sweat test value, no clear genotype-phenotype correlation was observed. DB should not be considered a classical autosomal recessive CFTR-RD. Moreover, although further investigations are necessary, we proposed a new class of "Non-Neutral Variants" whose impact on lung disease requires more studies.