Table 2

BRCA1 and BRCA2 mutations in women with breast cancer, women with benign breast disease (BBD), and unaffected control women

MutationsaBreast cancer (n = 645)BBD (n = 342)Controls (n = 319)RRb (95% confidence interval)RRc (95% confidence interval)
n%n%n%
BRCA1
 None59191.631592.128990.61.0 (Reference)1.0 (Reference)
 Group 381.210.330.91.3 (0.4, 6.0)0.4 (0.02, 3.4)
 Group 2396.1267.6278.50.7 (0.4, 1.2)0.8 (0.4, 1.5)
 Group 171.100.000.04.7 (1.5, ∞)d
BRCA2
 None57288.731792.729692.81.0 (Reference)1.0 (Reference)
 Group 3253.982.392.81.4 (0.7, 3.3)0.7 (0.2, 2.0)
 Group 2416.3164.7134.11.6 (0.9, 3.2)1.1 (0.5, 2.4)
 Group 171.110.310.33.6 (0.6, 68.0)1.0 (0.04, 27.0)
BRCA1/BRCA2
 None52280.929285.426884.01.0 (Reference)1.0 (Reference)
 Group 3 only294.582.3113.51.4 (0.7, 2.9)1.6 (0.6, 4.4)
 Group 28012.44112.03912.21.0 (0.7, 1.6)1.1 (0.7, 1.8)
 Any Group 1142.210.310.37.2 (1.4, 130)1.0 (0.04, 28.8)
  • a Group 1: Frameshift and splice-site mutations.

    Group 2: Missense changes, single amino-acid deletions and intronic changes ≤40 bases from coding region.

    Group 3: Silent changes, intronic changes >40 bases from coding region and changes after the BRCA2 polymorphic stop codon at amino acid 3326.

  • b Relative risks (RR) of breast cancer in relation to type of BRCA1 or BRCA2 mutation. Breast cancer cases compared with unaffected control women.

  • c Age adjusted relative risks (RRs) of BBD in relation to type of BRCA1 or BRCA2 mutation. Women with BBD compared with unaffected control women.

  • d Median unbiased estimate computed where sample size is 0.