Unmasking a novel frameshift BRCA 2 gene deleterious variant in TNBC setting: a possible candidate for poly (ADP-Ribose) polymerase inhibitors

Triple negative breast cancer (TNBC) is the most difficult form of breast cancer (BC) with limited treatment options. The BRCA2 is a tumor suppressor gene and presence of a pathogenic gene mutation can disrupt its function, leading to an increased risk of breast, ovarian, pancreatic, prostate and other cancers. The current study describes a case of 42-year-old pre-menopausal female with complete bilateral mastectomy with TNBC phenotype. Germline, Next Generation Sequencing (NGS) unmasked a novel BRCA2 gene, inDel variant. Cross-platform validation via targeted Sanger sequencing technology, confirmed the NGS data findings. Also, various bioinformatic tools predicted the variant to be “Deleterious/Damaging/Pathogenic” in nature as it resulted in a premature truncated protein. To our knowledge, the detected BRCA2, exon-10 mutation is a clinically significant gene variant in a high-grade bilateral TNBC setting, being reported from India (a global arena of TNBC cases). The variant has not been reported previously in any major clinical variant databases available. Hence, the detected BRCA2 gene variant has been submitted to ClinVar database for global access and review. Also, the detected BRCA2 gene pathogenic variant makes the patient a likely candidate for targeted PARP inhibitor’s in the presented clinical setting. The present study, illuminates the significance of NGS technology in cancer care in the era of “personalized medicine” which brings a novel actionable target to fore.