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Table 2 Threshold for probability of BRCA1/BRCA2 mutation

From: Future possibilities in the prevention of breast cancer: Intervention strategies in BRCA1 and BRCA2 mutation carriers

Chance that a mutation is present*

Clinical criteria

<10%

All single cases of breast or ovarian cancer

10%

Single breast cancer cases aged <35 years

>10-≤ 30%

Two breast cancer cases aged <50 years

 

One breast cancer case aged <40 years in an

 

Ashkenazi jew

≤ 50%

Three breast cancer cases aged <50 years

 

Four to five breast cancer cases, no ovarian cancer

 

One breast and ovarian cancer case

>50%

More than one breast and ovarian cancer case

 

At least four cases of female/male breast cancer

 

More than six female breast cancer cases

  1. *The chance of detecting a mutation is lower, because at least 15% of mutations are regulatory (ie they are not in the coding region of the gene that is the area tested), and the genetic screening methods are approximately 80% sensitive if sequencing is not used. Cases refer to first-degree relatives or first/second-degree relatives if multiple cases. Data from [7**,16,19,21,23,25,72].