Hereditary Nonpolyposis Colorectal Cancer (HNPCC)
Bob
Bob was cancer-free but his father had been diagnosed with
colorectal cancer around the age of 50. When Bob's brother
developed colorectal cancer at a fairly early age, his physician
offered genetic testing to the family. Bob's brother tested
positive for a gene mutation that causes hereditary nonpolyposis
colorectal cancer
(HNPCC)-HNPCC
is an inherited cancer syndrome that leads to an increased risk for
colon cancer, along with other
HNPCC-related
cancers. Bob wanted to undergo genetic testing to know his own
cancer risk, as well as to provide his children information about
their cancer risk. Bob said, "I wanted my children to know whether
or not they could potentially have the defective gene." He
underwent testing for the same gene mutation found in his brother.
Bob tested negative and learned he did not have HNPCC. He was
relieved not only for himself, but also for his three children.
Despite their strong family history of cancer, Bob and his children
are not at an increased risk for cancer and can follow general
population screening guidelines.
Familial Adenomatous Polyposis (FAP)
Jane
Jane's father was clinically diagnosed with an inherited
colorectal cancer syndrome called familial adenomatous polyposis
(FAP) because he had hundreds of polyps in his colon. Jane and both
her siblings developed colon polyps as well and were also diagnosed
with FAP. When Jane learned about the availability of genetic
testing, she chose to be tested for an APC mutation.
Although it didn't necessarily change her medical management, she
hoped it would determine whether or not her son and daughter were
affected with FAP. Her children were around the age of 10 and she
wanted to know whether or not they should begin having colon
screening, which is recommended to begin between the ages of 10 and
12 in FAP. After all, if they didn't need annual procedures at such
a young age, she wanted to avoid putting them through it.
Jane's genetic testing showed a mutation in the APC gene. Her son then tested negative for this mutation and, as a result, did not have to undergo annual colon screening starting at such an early age. He was reassured that, despite the history of FAP in his family, he was at the general population risk for colorectal cancer. Jane's daughter, however, tested positive for the APC mutation. Jane and her daughter now get their sigmoidoscopies together every six months. Her daughter recently had surgery to remove her colon. Jane said, "The result of the genetic testing didn't change anything in my medical management but it did make a difference with my children… It was a real relief knowing I didn't have two children to go through surgery and medical testing with… I think having genetic testing has been beneficial in our situation. With the blood test, we already knew who was at risk in our family situation and who wasn't."
Attenuated Familial Adenomatous Polyposis (AFAP)
Betty
At age 40, Betty was diagnosed with a spastic colon and noticed
some rectal bleeding. When her gastroenterologist performed a
colonoscopy, he found and removed multiple polyps in her colon.
Betty was surprised as she had never heard of such a thing. After
her colonoscopy, she contacted her parents and told them about her
colon polyps. Her parents volunteered that Betty's uncle had
undergone surgery to remove his colon after many polyps were
discovered by his physician. As she explored her family history in
more depth, she found that many of her relatives had been diagnosed
with multiple polyps as well but no one had ever volunteered the
information. Due to her personal and family history of multiple
colon polyps, Betty underwent genetic testing for attenuated
familial adenomatous polyposis (AFAP), an inherited cancer syndrome
characterized by an increased risk of colorectal polyps and cancer.
Betty tested positive for an APC mutation and now
undergoes more frequent colonoscopies in order to remove her polyps
and prevent colorectal cancer.
Curtis
Curtis' physician suspected that he had attenuated familial
adenomatous polyposis (AFAP) because of the multiple polyps that
were found in his colon. Curtis was offered genetic testing for the
APC gene and tested positive. Curtis said, "The main thing
for me was that confirmation of yes I have it, I do have the
mutated gene, and know I know what to do for it." His physician
advised him that his chances of having colorectal cancer by the age
of 50 or 60 were very high. As a result, the physician recommended
surgery to remove Curtis' colon before the age of 50. Curtis said
he appreciated the genetic testing because "knowing the fact that I
did have that mutation, I was able to take the steps through the
colonoscopies, through the EGD scopes, to do what I could to avoid
further problems." Curtis has been encouraging his two children to
undergo genetic testing for the APC mutation as well so
that they will be aware of their risk for colorectal polyps and
cancer.
A genetic test for hereditary nonpolyposis
colorectal cancer (HNPCC)
A genetic test for adenomatous polyposis
syndromes
