Mutational landscape of BRCA gene mutations in Indian breast cancer patients: retrospective insights from a diagnostic lab

Abstract

Presence of Germline mutations in the BRCA1 and BRCA2 genes is the most significant epidemiological factor for breast cancer (BC), where germline BRCA1 (gBRCA 1) mutation increases the risk for BC by 59–87% and gBRCA 2 mutation increases the risk by 38–80%. In this retrospective study, we have analyzed NGS-based genetic data for samples received at our laboratory for genetic testing over a three-year period to understand the prevalence and pattern if any of BRCA1 and BRCA2 mutations in Indian breast cancer patients. BRCA gene sequencing using NGS was performed in 395 consecutive cases of BC referred for testing to our lab between 2021 and 2023. Genetic analysis of mutations BRCA 1 and BRCA 2 genes resulted in 115 (29%) positive patients. Out of 115 patients, 79 reported BRCA1 mutations, whereas 36 had BRCA2 mutations. Exon 10 (57.3%) of BRCA1 and exon 11 (52%) of BRCA2 were the most mutated exons observed in this study. The c.1961delA (26.4%) variant, followed by the c.68_69delAG (22.7%) variant in BRCA1, and the c.6373delA (20.5%) variant in BRCA2, were the most common mutations found in our study. Our data shows positive correlation of younger age group (20–45 years) with BRCA positive status (Chi-square p value = 0.001). BRCA mutation prevalence was 29.1% in our data which is higher than Western countries. Based on our findings BRCA screening looks imperative for women with BC especially younger women (< 50 years), as family history based BRCA testing would miss out many BRCA positive candidates which could benefit from PARP therapy options.