Background: Breast cancer (BC) is the most common cancer reported in females in Oman and usually occurs at a relatively younger age, presents at an advanced stage and behaves aggressively. BC occurs in hereditary and sporadic forms. Although germ-line mutations in BRCA1 and BRCA2 genes are rare in sporadic cases compared with hereditary cases, molecular alterations, such as loss of heterozygosity, and CpG methylation, are common. In this study, we investigated the types of molecular alterations associated with hereditary and sporadic BRCA1-associated BC in Omani patients.
Methods: We obtained clinical data and samples from 43 sporadic BC patients. The selection of cases was made based on the following criteria: aged ≤ 40 years, or bilateral breast cancer, or estrogen and progesterone receptor negative status, and HER-2/neu negative (Triple Negative phenotype) status. Screening for molecular alterations was performed by direct sequencing, multiplex ligation-dependent probe amplification (MLPA).
Results: Genomic deletions and duplication in the BRCA1 gene were identified in four female patients. Two patients carried exon 1 and 2 deletions and two showed exon 1 and 2 duplication. Screening for mutation by direct sequencing revealed three polymorphisms in exon 11. Two of these polymorphisms are nonsynonymous (rs1800704, rs799917) and one is synonymous (rs1800740).
Conclusion: The current pilot study detected previously described gene rearrangements and polymorphisms involving the BRCA1 gene and no seemingly pathogenic missense mutations were elucidated.
Keywords: BRCA1, breast cancer, mutation, polymorphism, Omani, Arab.