ABSTRACT
However, almost half of families with multiple cases of breast cancer only
(site-specific breast cancer families) do not have an identifiable BRCA1 or
BRCA2 mutation. l Reasons why families with multiple cases of breast cancer only may not
have an identifiable BRCA1 or BRCA2 mutation include (i) the cluster of
cancers is a chance event, (ii) the individual tested may be a phenocopy
(i.e., the tested individual has a sporadic cancer unrelated to an inherited
familial predisposition), (iii) the inherited predisposition is due to a
mutation in an as yet undiscovered cancer predisposition gene, or
(iv) currently used mutation techniques are unable to detect a mutation that
is present within BRCA1 or BRCA2.
