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Table 1 BRCA1/2 mutation frequencies according to family structure

From: Spectrum and prevalence of BRCA1/2 germline mutations in Pakistani breast cancer patients: results from a large comprehensive study

Risk group Phenotype of families No. of families No. of families with mutations (%) in
BRCA1 BRCA2 BRCA1/2
Small-range LGRs All Small-range LGRs All
  All families 539 101 (18.7) 9 (1.7) 110 (20.4) 23 (4.3) 0 (0) 23 (4.3) 133 (24.7)a
Female breast cancer families 447 67 (15.0) 7 (1.6) 74 (16.6) 18 (4.0) 0 (0) 18 (4.0) 92 (20.6)
A1 1 case ≤ 30 years 203 20 (9.8) 2 (1.0) 22 (10.8) 3 (1.5) 0 (0) 3 (1.5) 25 (12.3)
A2 2 cases, >1 diagnosed ≤50 years 131 20 (15.3) 4 (3.0) 24 (18.3) 6 (4.6) 0 (0) 6 (4.6) 30 (22.9)
A3 >3 cases, >1 diagnosed ≤50 years 113 27 (23.9) 1 (0.9) 28 (24.8) 9 (8.0) 0 (0) 9 (8.0) 37 (32.7)
A4 Male breast cancer families         
>1 case of male breast cancer 27 1 (3.7) 0 (0) 1 (3.7) 4 (14.8) 0 (0) 4 (14.8) 5 (18.5)
B Breast-ovarian cancer families         
>1 breast cancer and >1 ovarian cancer 65 33 (50.8) 2 (3.0) 35 (53.8) 1 (1.5) 0 (0) 1 (1.5) 36 (55.4)
  1. LGRs large genomic rearrangements
  2. aIncluding 57 previously reported families [11, 18]