BRCA1/2 mutation spectrum in Armenian patients with breast and ovarian cancers

The aim of the study was to compare the spectra of pathogenic BRCA1 and BRCA2 variants in patients with hereditary breast cancer (BC) and ovarian cancer (OC) from two groups of ethnic Armenians: Yerevan and cities of southern Russia.Material and Methods. 106 BC patients from the V.A. Fanardjian National Centre of Oncology (Yerevan, Republic of Armenia) and 117 BC and OC patients of Armenian origin who were referred to the Petrov National Medical Centre of Oncology (St. Petersburg, Russia) from several cancer centers of Russia (Krasnodar, Sochi, Pyatigorsk) were included into the study. The coding sequences of BRCA1 and BRCA2 genes were analyzed by the method of targeted high-throughput sequencing.Results. Pathogenic variants of BCRA1 and BCRA2 genes were detected in 16/106 (BRCA1: n=9, BRCA2: n=7; 15%) BC patients from Yerevan. The only recurrent mutation was the BRCA1 nonsense variant c.5444G>A [W1815X], accounting for 44% of all pathogenic alleles identified. In patients of Armenian origin from Russia, pathogenic BRCA1/2 variants were detected in 16/117 (14%) individuals (BRCA1: n=6, BRCA2: n=10). The proportion of samples with mutations was 13% in the group of BC patients and 19% in the group of OC patients. 75% of pathogenic alleles were represented by five recurrent mutations: BRCA1 c.2649_2650insGGCA, BRCA2 c.2808_2808_2811delACAA, BRCA1 c.4065_4068delTCAA, BRCA2 c.9027delT and BRCA2 c.8437G>T [G2813X]. The independent origin of the pathogenic BRCA2 c.2808_2808_2811delACAA variant in Armenian and non-Armenian patients was shown.Conclusion. A significant difference in the spectrum of BRCA1/2 mutations between Armenian patients from Yerevan and patients from southern regions of Russia was found. This should be taken into account when developing diagnostic programs.