Spectrum and Prevalence of BRCA1/BRCA2 Variants in Aegean Region Hereditary Breast and Ovarian Cancer Cases

In Western populations, 5–10% of breast cancer cases are hereditary, primarily due to pathogenic germline variants in BRCA1 and BRCA2 genes. Women carrying these variants have a lifetime risk of 40–57% for BC and 18–40% for ovarian cancer. This study aims to investigate the prevalence and distribution of BRCA1 and BRCA2 variants among hereditary breast and ovarian cancer cases in the Aegean region of Turkey. In this retrospective study, the medical records of 157 hereditary breast and ovarian cancer cases who presented to the Medical Genetics Clinic at Aydın Adnan Menderes University between 2013 and 2019 were reviewed. BRCA1 and BRCA2 gene analyses for these cases were performed using Sanger sequencing. The results were analyzed by collecting demographic and clinical data, including tumor characteristics and family history. Pathogenic or likely pathogenic variants were identified in 17 cases (11%) for BRCA1 and 6 cases (4%) for BRCA2. The most common BRCA1 variants were c.66dupA and c.5266dupC, while BRCA2 variants exhibited greater heterogeneity, with no recurrent variants. Breast cancer (72.6%) was the most frequent diagnoses, with invasive ductal carcinoma as the predominant histological subtype. The study underscores the importance of population-specific genetic testing strategies to identify BRCA1/2 variants. The findings reveal a unique variant spectrum in the Aegean Region population, highlighting the absence of globally common variants and the need for comprehensive genetic counseling to improve risk assessment and management for hereditary breast and ovarian cancer patients.