Biomedical Engineering Reference
In-Depth Information
Breast and Ovarian Cancer
Genetic changes linked to an increased risk of breast and ovarian
cancers are found in only about one in ten of women with these
cancers. Everyone inherits two copies of the
BRCA
1 and BRCA2
genes (the
breast cancer genes
), but mutations in one copy mean
that a woman has 3-7 times greater a risk of developing breast or
ovarian cancer. In family members of a woman diagnosed with
breast or ovarian cancer due to one of the mutated forms of
BRCA1 or BRCA2, genetic testing may allow relatives to find out
if they have inherited an increased risk for breast or ovarian
cancer. The options for those with a positive test are not simple or
entirely effective, however. More frequent and thorough physical
exams will possibly detect a cancer at an earlier, more treatable
stage. Some women choose to have surgery to remove ovaries and
both breasts before cancer has a chance to set in. These are drastic
steps that do not even guarantee that a tumor will not develop,
because it is surgically impossible to remove all of the tissue that
might become cancerous. Treatment with drugs to reduce the risk
is not consistently effective in those with the BRCA1 and BRCA2
mutations. Given that these treatment options are not completely
effective, the psychological disturbance caused by a positive test
may be greater than the peace of mind obtained from a negative
test result. Before the test is done, physicians and families need to
consider the consequences for the whole family if the woman
diagnosed with breast cancer is tested.
Huntington Disease
Huntington disease
presents an enormous family challenge because
the symptoms do not develop until later in life. The mutated gene
is
dominant
(as opposed to
recessive
), which means that the risk of
developing the disease is 100% for people who inherit just one
copy of the mutated form of the gene. Children of a person with
Huntington disease have a 50% chance of inheriting the mutated
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