BRCA1 and breast cancer: In Group I-B (breast cancer diagnosed ≤ 35 years old or ≤ 40 years old in the case of a noninformative family), pathogenic variants in the BRCA1/2 genes were detected in 11.1% of patients, and in Group I-E (high-grade serous ovarian, fallopian tube or primary peritoneal cancer), they were detected in 10.81% of patients.