Mutation in Exon2 of BRCA1 Gene in Adult Bengali Bangladeshi Female Patients with Breast Cancer: An Experience from Two Tertiary-Care Hospitals

Background: The occurrence rate of BRCA1 mutations is found to be high in South Asian countries where early onset of breast cancer is common. In Bangladesh, noticeable percentage of patients experience breast cancer in their reproductive ages. The objective of this study was to identify any mutation in exon2 of the BRCA1 gene in adult Bengali Bangladeshi female patients with breast cancer. Methods: In this cross-sectional descriptive study, the genomic DNA was extracted from the blood of adult fifty Bengali Bangladeshi female breast cancer patients. The whole region of exon2 of the BRCA1 gene was amplified and the amplified DNA products were sequenced using Sanger sequencing. The raw chromatogram data were analyzed using Chromas software, and analyzed sequences were compared with the NCBI RefSeq database by BLAST search. The resultant amino acid change was detected by MEGA X software. Results: We found the mean age at diagnosis 44.66 years, whereas 96% of patients were married, 90% were multiparous and 86% breastfed their children. All patients had unilateral breast cancer and among them 94% had invasive ductal carcinoma. Only 24.5% of the patients had associated omorbidity. The family history of breast cancer or other BRCA-associated cancer was positive only for 4% of patients. A total of five mutations were identified all of which caused by substitutions. Among them three were nonsynonymous and two were synonymous. Only 2.5% of the patients, within the age group of 18-50 years, were found to have mutations in their blood, whereas 26.66% of the patients above 50 years found to have mutations in this study. Conclusions: Among this small sample size, we found five mutations in exon2 of the BRCA1 gene and this indicates the necessity to find out the mutation spectra of the BRCA1 gene in the Bangladeshi population.