The Genetic Analysis of Cystic Fibrosis Patients with Seven Novel Mutations in the CFTR Gene in the Central Anatolian Region of Turkey

BACKGROUND: Cystic fibrosis, a pulmonary disease which is an autosomal recessive, inherited, multisystemic genetic disease commonly seen in the Caucasian race, is the most frequent cause of mortality and morbidity. So far, more than 2000 disease-causing gene variants have been found and this number has been increasing with the studies conducted. Although there is not yet enough data that include the Turkish population, the recent increase of studies is noteworthy. AIMS: To discover the genetic variation in patients diagnosed with cystic fibrosis in the Central Anatolian region. STUDY DESIGN: Cross-sectional study. METHODS: The study was carried out in the Central Anatolian region in 3 pediatric pulmonology departments (Kayseri, Konya, and Ankara) in Turkey between July 2014 and December 2017. The Sanger and Next Generation Sequence analyses were used for exon and exon–intron boundaries in the cystic fibrosis transmembrane conductance regulatory (CFTR) gene, and in selected patients, mutation analysis was performed using the Multiplex Ligation-dependent Probe Amplification technique for large deletions and duplications. RESULTS: CFTR gene analysis was performed for 316 patients and 215 of them were genetically diagnosed with cystic fibrosis. Sixty-three different variants were defined in these patients and 7 of these were large deletions/duplications detected with the MLPA method. The most frequent variants were F508del (29.6%), G85E (8.2%), N1303K (8.2%), Y515* (7.5%), and G542* (3.4%). CONCLUSION: Using sequencing and Multiplex Ligation-dependent Probe Amplification methods, the identification of seven new mutations that were not previously reported in the literature contributes to a better understanding of the heterogeneous nature of CFTR mutations in the Turkish population. When no mutations are detected (pathogenic/probably pathogenic) in clinically compatible cases, Multiplex Ligation-dependent Probe Amplification analysis contributes significantly to the diagnosis.