Spectrum and frequency of BRCA1, BRCA2, CHEK2, PALB2, RAD50 mutations in breast cancer patients in the Republic of Bashkortostan

Aim. To assess the spectrum and frequency of mutations in patients with hereditary breast cancer from the Republic of Bashkortostan. Methods. The material for the study was sections of fresh frozen, formalin-fixed and paraffin-embedded tumor tissue from 100 unrelated patients with a histologically confirmed diagnosis of breast cancer. The study was carried out using two methods: real-time polymerase chain reaction and next-generation sequencing-NGS. Results. By using real-time polymerase chain reaction (PCR), the 5382insC mutation in the BRCA1 gene was detected in 12 cases. By using a next-generation sequencing method (NGS), highly penetrant mutations in BRCA1, BRCA2, CHEK2, PALB2 and RAD50 were revealed in 16 patients. In total, these methods detected mutations in 28 patients. Out of a total of probands in the BRCA1 gene, mutations were detected in 13 patients, that included 12 patients with the 5382insC mutation, and 1 patient with c.3143delG. In the BRCA2 gene, mutations were revealed in 3 patients, of which c.6621_6622del in 2 patients and c.-39-1_-39delGA in 1 patient. Mutations in CHEK2 were detected in 5 patients: c.470T>C in 3 patients, c.444+1G>A in 2 patients. The 1592delT mutation in PALB2 was found in 4 patients. The c.2157delA mutation in RAD50 was detected in 3 patients. Conclusion. Pathogenic mutations in BRCA1/2, CHEK2, PALB2 and RAD50 were found in 28 patients with a hereditary feature of the disease; the identification of highly penetrant mutations in probands allowed us to determine their relatives, probable carriers of mutations, which were referred for genetic counselling.