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Table 3 Frequencies of BRCA1 and BRCA2 mutations in relation to the classification of patients and families

From: High proportion of recurrent germline mutations in the BRCA1 gene in breast and ovarian cancer patients from the Prague area

Classification Number of patients/families No. of mutations in BRCA1 (%) No. of mutations in BRCA2 (%) No. of BRCA1 + BRCA2 mutations (%)
Cases without a family history of breast and ovarian cancer     
   Breast cancer before 36 31 3 (9.7) 1 (3.2) 4 (12.9)
   Bilateral breast cancer before 51 3 1 (33.3) - 1 (33.3)
   Breast and ovarian cancer 7 1 (14.3) - 1 (14.3)
   Medullary breast carcinoma 14 3 (21.4) - 3 (21.4)
Breast cancer families (HBC)     
   2 breast cancer cases 25 5 (20.0) 2 (8.0) 7 (28.0)
   ≥3 breast cancer cases 35 6 (17.1) 1 (2.9) 7 (20.0)
   Total 60 11 (18.3) 3 (5.0) 14 (23.3)
Breast and ovarian cancer families (HBOC)     
   1 breast cancer and 1 ovarian cancer 5 1 (20.0) 2 (40.0) 3 (60.0)
   ≥3 breast and ovarian cancer cases 27 14 (51.9) 2 (7.4) 16 (59.3)
   Total 32 15 (46.9) 4 (12.5) 19 (59.4)
Ovarian cancer families (HOC)     
   ≥2 ovarian cancer cases 4 1 (25.0) 1 (25.0) 2 (50.0)
  1. HBC, hereditary breast cancer; HBOC, hereditary breast and ovarian cancer; HOC, hereditary ovarian cancer.