The CanRisk Tool will sometimes predict a high residual
BRCA1/BRCA2
mutation carrier probability when
the index
the target (subject of the risk calculation) has had a negative mutation search. This can happen even if the
BRCA1/BRCA2
mutation search sensitivities were set to 0.95 (95%).
Intuitively
For example, it’s tempting to think that if the
index
target has had a negative mutation search with the BRCA1/BRCA2 mutation search sensitivities set to 0.95 (95%), then the resulting BRCA1/BRCA2 mutation carrier probabilities should be very small. However, in practice, the
BRCA1/BRCA2
mutation search sensitivities
are more closely related to
reflect the probability of observing a mutation rather than the probability of carrying one. Also, the
BRCA1/BRCA2
mutation carrier probabilities predicted by the program are conditional probabilities, which take multiple factors into account. This explains why it’s possible to have a large residual
BRCA1/BRCA2
mutation carrier probability under these circumstances.