Genetic characterization of BRCA1 and BRCA2 variants in cancer and high-risk family screening cohorts in the UAE population
Germline BRCA1/2 (gBRCA1/2) variants are strongly associated with hereditary cancers, and screening for these variants in high-risk populations is recommended for personalized management. This study aims to comprehensively characterize gBRCA1/2 variants in cancer and family screening cohorts from the Dubai Emirate, UAE. A total of 443 patients with breast, ovarian, prostate and pancreatic cancer were tested for gBRCA1/2 variants from 2017 to 2022 using whole-gene sequencing, and data were analysed using variant interpretation and in-silico prediction tools. All BRCA1/2 variants were classified as P/LP or variants of uncertain significance (VUS) according to ACMG guidelines. In the cancer cohort, 38 out of 306 patients harboured gBRCA1/2 P/LP or VUS variants. Of these, 23 (7.5%) were classified as BRCA1/2 P/LP, while 15 (4.9%) were categorized as VUS. These variants were predominantly observed in estrogen receptor-positive/progesterone receptor-positive (ER + /PR +) and triple-negative breast cancer patients. Common BRCA1 P/LP variants included deletion frameshift variants (c.4065_4068del, c.68_69delAG, c.3228_3229delAG), an insertion frameshift variant (c.1140dup), and a nonsense variant (c.5251C > T). BRCA2 P/LP variants included a nonsense variant (c.5645C > A), a missense variant (c.7007G > A), and a deletion frameshift variant (c.2254_2257del). In the family screening cohort, 14 out of 137 samples harboured BRCA1/2 P/LP orVUS. Of these, five (3.6%) were classified as P/LP, while nine (6.6%) were VUS. Pathogenic BRCA1 variants included deletions (c.4065_4068del, c.3756_3759del) and a nonsense variant (c.5095C > T), while BRCA2 PVs included a deletion frameshift (c.771_775del) and a novel missense variant (c.8377G > A). In both cohorts, novel distinct variants were observed. gBRCA1/2 variant prevalence in cancer and family screening cohorts can serve as beneficial personalized tool for management and treatment of cancer patients. Larger studies from other emirates of UAE will serve as a foundation for robust risk assessment and implementation of treatment and prevention strategies.