Breast cancer risk associated with BRCA1/2 variants in the Pakistani population.

BACKGROUND: Majority of the BRCA1 and BRCA2 mutations are associated with the risk of sporadic and familial breast cancer. Since these genes are significant in DNA repair mechanisms, we focused homology-directed DNA repair (HDDR) and BRCA complex.

METHODS: We selected BRCA1 variant (rs80356932, 4491C/T) and BRCA2 variant (rs80359182, 319T/C) from the interaction region of BRCA complex and studied in 100 breast cancer patients and 100 controls using tetra-ARMS-PCR.

RESULTS: Here we show that BRCA1 and BRCA2 variants are significantly associated with high breast cancer risk (BRCA1 rs80356932; Genotype T/T OR 8.66, 95% CI 3.16-23.71, p < 0.0001; Allele-T, OR 2.48, 95% CI 1.62-3.81, p < 0.0001 and BRCA2 rs80359182; Genotype C/C OR 4.32, 95% CI 1.95-9.53, p = 0.0001; Allele-C, OR 2.19, 95% CI 1.43-3.34, p = 0.0002). Additionally, bioinformatics analysis showed that BRCA2-tryptophan > arginine substitutions result in altered interaction of BRCA1/PALB2/BRCA2/protein complex and impaired HDDR pathway. We also observed that breast cancer risk was significantly increased in over-weighted and obese women.

CONCLUSIONS: Our results indicate that high risk of breast cancer is significantly associated with BRCA1 and BRCA2 variants, and mutations may alter the protein interactions of BRCA complex that results in tumor genesis.