Table 1 BRCA1/2 mutation frequencies according to family structure

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)