Table 2

Threshold for probability of BRCA1/BRCA2 mutation

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

^*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].

Eeles Breast Cancer Res 2000 2:283   doi:10.1186/bcr70