Introduction/Background The range and frequency of BRCA1/2 mutations in multinational regions might be different from regions with a predominance of the Slavic population. Most of the residents of the Republic of Bashkortostan are representatives of non-Slavic nationalities, that is one of the features of our population. Standard PCR (polymerase chain reaction) tests that were developed for the Slavic population may be associated with a large number of false negative results in regions such Bashkortostan.

This study aims to determine regional specificity of the frequency and spectrum of BRCA 1/2 mutations in women of Republic of Bashkortostan with HGSOC (high grade serous ovarian cancer).

Methodology In this study all women with HGSOC receiving treatment at Republican Clinical Oncology Center in Ufa since 2021 till 2023 were referred for BRCA testing. Both primary and recurrent diseases underwent testing. Tumor tissue paraffin blocks were obtained from 77 women and BRCA 1/2 genes were sequenced using next generation sequencing (NGS).

Results The average age of patients was 54,9 years (30–74). Thirty-three women (42.9%) had pathogenic BRCA 1/2 mutations. Of these mutations, 24 cases were represented as mutations in gene BRCA1 (72.7%), 9 cases as BRCA2 mutations (27.3%). The most common mutation was expectedly BRCA1:NM_007294.4:EXON20:C.5266DUP:P.(Q1756PFS*74):P.(GLN1756PROFSTER74) - 11 of 33 (33,3%). Other 22 cases were represented by rare mutations (66.7%) (table 1).

Conclusion In non-Slavic regions of Russia the spectrum and frequency of BRCA mutations in HGSOC might show its own specificity. A large number of rare mutations is common. Using NGS is more preferred in such regions.

Disclosures The authors declare no conflict of interest