title: Validation of CFTR intronic variants identified during cystic fibrosis population screening by a minigene splicing assay.
abstract: BACKGROUND
  Cystic fibrosis, caused by mutations of the CFTR gene, is the most common autosomal recessive condition in the European population and there are specific screening programs aimed at investigating healthy carriers. They are usually articulated in two steps: initially individuals are screened with a panel of the 20-50 most common CFTR mutations; the second step is offered to partners of carriers who were found negative at the first test and consists in the analysis of the entire CFTR gene. This strategy provides high sensitivity, however, it often identifies novel variants (especially in introns) of unknown significance. Establishing the pathogenicity of these variants of the CFTR gene is not a simple task.
  
  
  METHODS
  We have examined five CFTR intronic variants of unclear significance (c.274-6T>C, c.744-6T>G, c.1117-64G>A, c.2620-26A>G, and c.3468+51C>A) using a functional splicing assay based on hybrid minigenes.
  
  
  RESULTS
  Four out of five variants (including c.2620-26A>G which was previously reported as a possible splice-site mutation) did not alter the correct splicing of the minigene and are likely to be neutral polymorphisms, whereas c.744-6T>G caused complete skipping of CFTR exon 7 and should be therefore regarded as a pathogenic CFTR mutation.
  
  
  CONCLUSIONS
  Hybrid minigenes assay are a simple and rapid tool to evaluate the effects of intronic variants without the need of analyzing patient's mRNA, and are particularly suited to analyze variants identified during population screenings.
authors.forename: Gianpietro
authors.initials: G
authors.lastname: Giorgi
authors.forename: Alberto
authors.initials: A
authors.lastname: Casarin
authors.forename: Eva
authors.initials: E
authors.lastname: Trevisson
authors.forename: Marta
authors.initials: M
authors.lastname: Donà
authors.forename: Matteo
authors.initials: M
authors.lastname: Cassina
authors.forename: Claudio
authors.initials: C
authors.lastname: Graziano
authors.forename: Luigi
authors.initials: L
authors.lastname: Picci
authors.forename: Maurizio
authors.initials: M
authors.lastname: Clementi
authors.forename: Leonardo
authors.initials: L
authors.lastname: Salviati
mesh_terms: D001681:Biological Assay / Q000379:methods / Q000592:standards; D003550:Cystic Fibrosis / Q000235:genetics*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D005820:Genetic Testing / Q000379:methods* / Q000592:standards*; D014644:Genetic Variation / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D007438:Introns / Q000235:genetics*; D009154:Mutation / Q000235:genetics; D012326:RNA Splicing / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*
chemical_list: D012333:RNA, Messenger; D019005:Cystic Fibrosis Transmembrane Conductance Regulator