New variants in the BRCA1 gene in Buryat Mongol breast cancer patients: Report from two families

The BRCA1 mutations that are endemic to the Slavic population of Russia have not been identified among indigenous peoples, including the Buryats, Tuvinians and Altaians with hereditary breast cancer. This study was aimed to identify the mutations that are responsible for the occurrence of hereditary breast cancer in the indigenous population of the Republic of Buryatia. Mutations in the BRCA1 gene were identified in blood samples by Sanger-based sequencing. We identified 11 polymorphisms (10 SNPs and 1 Indel) and 6 new unclassified sequence variants in the BRCA1 gene. In our study three new sequence variants (c.321T>A, c.366T>A, c.4357+2T>A) were found in position of previously described polymorphisms in dbSNPs: rs80357544 (c.321delT), rs190900046 (c.366T>G), and rs80358152 (c.4357+2T>C), respectively. Other three new sequence variants (c.3605A>G, c.1998A>C, and c.80+13A>C) have not been previously described in dbSNP, BIC and Human Gene Mutation Databases. We described six new sequence variants that have never been published in the literature or databases. Further studies are required to confirm the impact of new sequence variants on the risk of breast cancer in the Buryat Mongol population.