Molecular Diagnostics of Cystic Fibrosis in Serbia: Our Approach to Meet the Diagnostic Challenges

Background: High heterogeneity levels of cystic fibrosis transmembrane regulator (CFTR) are manifested in different populations. The aim of this study was to analyze comprehensively all mutations in the CFTR gene in Serbian patients with cystic fibrosis (CF) and to use the findings to propose a testing algorithm for the Serbian population. Materials and Methods: Cascade screening was employed to detect mutations in the CFTR gene of 90 patients suspected of having CF, using polymerase chain reaction (PCR), PCR-restriction fragment length polymorphism or PCR-mediated site directed mutagenesis, Sanger sequencing, and/or next-generation sequencing. Results: This is the first report for the Serbian CF population where single nucleotide polymorphisms, small insertions and deletions, large genome rearrangements, and copy number variants were analyzed in detail. A high degree of heterogeneity within the CFTR was documented among our cohort of 90 patients. We identified 19 CF-causing mutations and 3 with varying consequences, including a previously unreported deletion of the entire exon 11. Conclusion: Considering the spectrum and frequency of mutations found, we recommend a multistep sequencing algorithm in combination with evaluation of large rearrangements for future analyses of the CFTR gene in the Serbian population