AIM: The prevalence of BRCA1/2 pathogenic variants among Turkish breast cancer (BC) patients is not well-characterized. We specifically examine the age at onset and cancer sub-types concerning BRCA1/2 mutation status, focusing on patients with no family history of breast or ovarian cancer. METHODS: Peripheral blood samples were collected from 3184 BC patients applied to the Istanbul University Oncology Institute. Genetic testing for BRCA1/2 mutations was conducted using the Illumina MiSeq® platform, with variant classification performed according to ACMG criteria. RESULTS: Among the 3184 patients, 2764 (86.8%) were BRCA1/2-, while 247 (7.8%) were BRCA1 + and 173 (5.4%) were BRCA2 + . The mean age at BC onset was significantly lower in BRCA1 + (39.73 years) and BRCA2 + (41.07 years) patients compared to BRCA1/2- patients (43.17 years, p < 0.001). Among patients with no family history, HER2 positive cases had a significantly higher mean age at onset than Triple-Negative Breast Cancer(TNBC) cases (41.78 years vs. 40.44 years, p = 0.017). CONCLUSIONS: This study highlights the strong association between BRCA1/2 + mutations and earlier BC onset, particularly in patients with no family history of breast or ovarian cancer in Türkiye.