LWBK1006-14 LWW-Govindan-Review November 24, 2011 11:28
Chapter 14•Genetic Counseling 159lesions. If Pauline’s sister undergoes clinicalBRCA1andBRCA2genetic
testing, then these results may change the interpretation of Pauline’s test-
ing. For example, if Pauline’s sister’s testing is positive for a mutation,
then Pauline’s testing would be interpreted as a true negative. If Pauline’s
sister’s testing is negative, then Pauline’s testing was of no clinical value
because the basis for disease remains unknown. Without prior knowl-
edge of the family’s gene mutation, Pauline’s negative testing may have
provided a false and dangerous sense of security.Answer 14.12. The answer is D.
The underlying genetic basis for cancer predisposition remains unknown.
Even though Pauline had negative genetic testing, it is not known whether
she inherited the disease causing gene mutation. As such, Pauline, and
her paternal family members, should continue to be considered at high
risk and followed accordingly. The clinician must return to the family
cancer history to determine her medical follow-up. The family history
is consistent with the clinical diagnosis of either the hereditary BRCA1
or BRCA2 syndrome. Pauline should follow the same recommendations
as families with a confirmed diagnosis of one of these syndromes, until
genetic testing proves informative for her family. Intensified surveillance
with mammography and breast MRI screening, beginning by 25 years of
age, is recommended. In studies of individuals with an increased breast
cancer risk, the combination of mammography and breast MRI proved to
be more effective in identifying abnormal breast lesions than mammogra-
phy alone. The combination of mammography and breast ultrasound for
women with an increased breast cancer risk is still under investigation.
In a 1997 study published by Giradello and colleagues in theNew
England Journal of Medicine,approximately one-third of all ordering
physicians misinterpreted the results ofAPCgene testing. The majority
of errors arose as physicians misinterpreted a negative test result when
the genetic basis for disease had not previously been established in a
given family. Ongoing genetics education is needed for practitioners who
assume the genetics care and testing of families with hereditary disease.Answer 14.13. The answer is B.
HNPCC (also known as Lynch syndrome) is primarily associated with a
high risk for colon and endometrial cancer and an increased risk for other
tumors including ovary, stomach, small intestine, hepatobiliary tract, uri-
nary tract, brain, and skin. Cervical cancer is not one of the known asso-
ciated cancer types. The life time risk for colon cancer is estimated to
range from 60–80% and for uterine cancer as high as 60% lifetime risk.Answer 14.14. The answer is D.
Peutz-Jeghers syndrome is characterized by the association of hyperpig-
mented macules, increased cancer risk, and gastrointestinal polyposis.
Blue/black macules may be found around the mouth, buccal mucosa, nos-
trils, eyes, and fingertips. These lesions may fade over time. Hamartoma-
tous polyps (Peutz-Jeghers type) most commonly occur in the small bowel