A wide methodological approach to identify a large duplication in CFTR gene in a CF patient uncharacterised by sequencing analysis

Background: PCR-based diagnostic procedures are not able to characterise 6% of CF alleles. Recently, the application of array-CGH and of CFTR mRNA analysis has allowed the identification of new copy number mutations and splicing defects, that account for 2% and 13% of CF alleles, respectively, in the Italian population. Methods: Here, we report the characterisation of a large duplication in CFTR gene through different methods: MLPA assay, RT-PCR and high-resolution array-CGH. Results: We identified a large duplication, involving exons 6b-16, in a patient heterozygous for F508del mutation. This duplication produces an abnormal transcript with an out of frame addition of 2244 nucleotides and leads to the insertion of 8 amino-acid residues in the protein, followed by a stop codon. Conclusions: We propose a wide methodological approach based on MLPA assay, RT-PCR and high-resolution array-CGH to routinely analyse CF patients uncharacterised for one or both CFTR alleles.