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Familial Adenomatous Polyposis

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Overview

What is Familial Adenomatous Polyposis (FAP)?
Familial Adenomatous Polyposis (FAP) is an inherited disease where a hundred or more small growths called polyps form on the large intestine. Untreated, it eventually leads to colon cancer, usually by the age of 40 years. The polyps usually begin to form in adolescence, but an individual may not feel symptoms until later in adult life, where they may notice blood in their poo, feel dizzy, or lose weight. If untreated, other symptoms that may develop include dental problems, tumors in connective tissue and duodenum (part of the small intestine), stomach, and other parts of the body.
FAP is caused by a mutation in a gene called APC. If one parent has a faulty APC gene, there is a 50% chance each of their children will develop FAP.
It is important to detect FAP risk as soon as possible. When detected early (in childhood or adolescence), people at risk will be tested often – when they develop 20 to 30 polyps, their doctor should recommend a colectomy – removing the part of the large intestine called the colon.

FAP is caused by a change in the APC gene. Source: RD Kennedy et al. 2014. Journal of Pediatric Surgery. Images created by Iconarray.com. Risk Science Center and Center for Bioethics and Social Sciences in Medicine, University of Michigan. Accessed 2016-06-20.

What is the genetic test?
Genetic testing allows us to identify people at risk of developing FAP. A mutation in a gene called APC causes FAP. People with known genetic changes in APC will develop FAP and eventually colon cancer if they do not receive the correct treatment. Genetic testing allows us to identify people at risk of FAP and to provide treatment that strongly reduces the risk of colon cancer.

How will this affect my health care?
If a person is found to be have a genetic risk of FAP, they will have regular health checks until they develop 20 to 30 growths (polyps) in the large intestine. After this happens, a doctor should recommend a colectomy – removing the part of the large intestine called the colon. This surgery has a very high success rate of preventing cancer. This surgery usually take place when a person is 15 or 16 years old, but can be performed in young children or infants.

Who is at risk?
FAP is rare, and develops in less than 1 in 7,000 people. However, if a person’s mother or father has a change in the APC gene that causes FAP, he or she has a 50% chance of getting the disease (i.e. a 1 in 2 chance). Similarly, if a person’s brother or sister has the APC risk gene, they will have a 50% risk of getting FAP.

Does my ancestry affect my risk?
People are at a slightly increased risk of FAP if they are of Asian and African ancestry.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Treatment

When detected early, surgical treatment for people with the APC risk gene is highly successful.

What are the treatments for FAP?
If the APC gene is detected when a person is young, they will be tested often to check for polyps. When the polyps do develop, and a person has 20 to 30 or more, their doctor should recommend a colectomy (removing the colon by surgery), which is very successful at reducing the risk of cancer.

Can treatments cause any problems?
The surgery to prevent colon cancer can cause problems depending on the procedure. Sometimes, as well as removing the colon, it may also be necessary to remove the rectum. If this is the case, then surgery is also needed to move the small intestine so that poo collects in a pouch near a person's groin.
If the surgery does not remove the rectum, this pouch is not needed, and there is less impact on quality of life.
For all people who have surgery to remove the colon, healing time can be quite long and uncomfortable.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Genetic Test

Why do a genetic test?
The major reason people develop FAP is that they inherit a faulty gene that causes it. Genetic testing tells us who is most at risk for developing FAP. Testing for certain genes is particularly important if they are considered to be 'medically actionable' - meaning test results can be used to improve health care.
In the embedded video, Dr. Dan Roden of Vanderbilt University discusses how genetic testing has begun to influence treatment of patients.

What is the test?
There are several types of genetic tests for risk of FAP. All genetic tests look at your DNA to try to identify faulty genes previously associated with FAP.
Many of the people who use this website are patients in hospitals who are part of the eMERGE network. These hospitals are using DNA sequencing to test patients for a number of diseases, including FAP, as recommended by the American College of Medical Genetics and eMERGE network members. Test results found to be medically ‘actionable’ (meaning they can be used to in patient health care) will be returned to patients.
Other types of testing for FAP include sigmoidoscopy and colonoscopy.
A sigmoidoscopy is a procedure to examine the sigmoid colon is a part of the large intestine nearest to the rectum. During this procedure, a doctor will insert a flexible tube inside the body, which has a small camera attached. At this point, a doctor may also take a small sample of tissue from the colon to carry out a biopsy to examine the tissue for evidence of FAP.
A colonoscopy is a very similar procedure, but checks the entire colon and rectum (not just the sigmoid colon).

I am concerned whether I should be tested or not, what should I do?
The decision to be tested might be one of the most important decisions you have to make. There are many things you may want to consider. For some people, genetic testing can have positive health benefits, while others may feel a lot of stress and worry. You can read more about these issues in the Concerns & Risks section. It may help to think about testing for a while before making a decision. You may also find it helpful to discuss issues with those close to you, or with your doctor/health professional.

What will the test result mean?
This test will tell your doctor whether you are at risk of developing FAP. We test for a number of other diseases, as recommended for testing by the American College of Medical Genetics and the eMERGE network. If you are found to be at risk, your doctor or genetic counselor should help you understand your health care options.

What happens if I am found to be at risk?
If you are found to be at risk for any of the diseases that we test for, a health professional at your llocal site will attempt to contact you as soon as possible. Once we contact you, your doctor or genetic counselor should help you understand your health care options.

What happens if I am NOT found to be at risk?
If you are found NOT to be at risk for any of the diseases that we test for, you will likely NOT be contacted. However, a small number of patients may receive a medical report with results, while other patients may be re-contacted about another research study
If you have not been rec-contacted, please DO NOT ASSUME that you have been tested. There are a number of reasons testing may not have happened yet. For example, studies can sometimes take a very long time to complete, and DNA samples are often not usable because of quality-control issues.

How is the test being performed?
Testing is performed on your DNA, usually from a blood sample. For many patients, your hospital or treatment center may already have some of your DNA stored in a biobank. You may be asked for an additional sample or be asked to give us permission to do testing on the existing samples.

Will it hurt?
For some patients, we may need an additional blood sample. Taking blood may cause some pain, bleeding or bruising at the spot where the needle enters your body. Rarely, taking blood may cause fainting or infection.

Is it safe?
There is a risk that you may experience pain or bleeding if you need to give an additional blood sample. Risks concerning privacy are discussed under Concerns & Risks.

How long will I have to wait for results?
Unfortunately, we cannot give an accurate estimate for the time you will have to wait for results - this will depend on the resources available at the location where you receive treatment and were tested.

Is this a standard test?
Although increasingly more common, this test is not yet standard, and is typically offered as part of a research study.

What type of test is this?
Is this test intended to help make a diagnosis? Yes
Is this test intended to predict a family history of disease? Yes
Is this test intended to check if I am a carrier for a particular disease? Yes
Is this test intended to screen for genetic disorders? Yes
Is this test intended to screen for disorders related to pregnancy? No
Is this test intended to screen for disorders related to newborns? No

Will I need to have this test done more than once?
No, you should not need to have this test done more than once. You will need to keep track of your testing result in order to share with all of your doctors, including those you see at other medical care centers.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Family

Will my genetic test results affect my family?
Your genetic test results may affect your family. In the embedded video, Maureen Smith, a researcher at Northwestern University, recommends first discussing genetic test results with your doctor. Your doctor may refer you to a genetic counselor, who can help you understand test results and guide you toward brochures and websites that can provide information for both you and your family.

  • Before your genetic test: Because genetic information is inherited, it is important to be aware that your genetic test results are often relevant to your family members as well. Results may indicate that you are at risk, or that you are a carrier (see below). Before you have a genetic test, it can be a good idea to think about if and how you would like to share results with your family. Your doctor or genetic counselor should be able to provide more information about this.
  • After your genetic test: For many of the diseases we test for, genetic test results may be relevant to your family members, as well as to you. You may be at risk, and you may be a carrier (see below). If you already have results, it is again important to think about sharing them with family. Again, your doctor or genetic counselor should be able to offer advice on how genetic testing may affect your family members.

Can you (briefly) explain heritability?
We each have about 24,000 genes, which carry the instructions for making and maintaining our bodies. For each gene we typically have two copies – one inherited from each parent. If genetic test results suggest you are at risk of developing a heritable disease, you will have inherited the risk from one or both your parents. Your brothers, sisters, children, parents, and other relatives may also be at risk of developing the same disease.
There are several ways we can inherit a genetic disease, which relates to whether it is recessive or dominant.

  • For a dominant condition, only one copy of a gene needs to be faulty to cause a disease. In this case, if you have one copy of a faulty gene, you may be at high risk of developing the disease. You could pass this faulty gene to one your child or children. FAP is a dominant condition.
  • For a recessive condition BOTH copies of a gene must be faulty to cause a disease. In this case, if a person has only one copy of a faulty gene, they may not be at much greater risk. However, they may pass the faulty gene to their children. Again, this person is called a carrier.
Please note that the Resources section provides links to a number of websites that provide a much more detailed explanation of inheritance! Learn.Genetics at the University of Utah have a much more detailed explanation, which we find quite good – you can check it out here.

What is a carrier?
As described above, each of us has two copies of each gene. For recessive genetic conditions, BOTH copies of the gene need to be faulty for the person to be at risk of developing the disease. If a person inherits one faulty copy and one normal copy, they are called a carrier. Although they should not be at greater risk, they may pass the faulty gene copy to their child or children. If they do, and the child also inherits a faulty gene copy from the other parent, that child will be at risk of developing the disease.

What family members could be affected?
If you have FAP, there is a 50% your child will too. Other family members are also at a much higher risk of having FAP.

My children are under 18 years of age – should they be tested?
The American College of Medical Genetics recommend testing children for most of the diseases listed on this website. For FAP and the APC risk gene, this is certainly the case: it is very important to identify risk early in life, as this can have important consequences on whether a patient will develop colon cancer.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Concerns & Risks

What Should I Do If I Have Concerns About Genetic Test Results?
If you are concerned about genetic test results you have received, you should discuss your concerns with your doctor. Your doctor should be able to explain results to you, and may recommend you to a genetic counselor or another doctor that can further help you understand your results. Maureen Smith, a researcher at Northwestern University, discusses these concerns in the embedded video.

Is there a reason why I may be a specific risk?
For most of the disorders discussed on this site, the American College of Medical Genetics recommends genetic testing for individuals with available genetic data.

Are there any implications for having children?
Yes, please see the Family Section

Can I expect to experience emotional consequences related to my test result?
A range of reactions are possible and normal. Some patients may experience anxiety or other negative reactions related to genetic testing and results. If this is the case, please discuss with your doctor, who can address your concerns and refer you another health professional if required.

Can I expect to experience social consequences related to my test result?
Some people may feel that there is a stigma attached to having a genetic disease. If you do experience or anticipate any negative social reactions, please discuss with your doctor who can address your concerns.

Can I expect to experience an increase in anxiety?
Many individual experience increased anxiety related to genetic testing. Again, please discuss with your doctor if this is the case.

Are there any implications in terms of discrimination arising from the test result?
Health insurance companies are prevented by law from discriminating against you based on your genetic test results. However, the same law does not apply to long-term disability insurance or to life insurance. Maureen Smith, a researcher at Northwestern University discussed these issues in the video on this page.

If I am found to be at increased risk for developing a disease, are there similar health implications for my family?
Yes, your results may have similar health implications for your family. Please see the Family section.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Sharing

Should I tell other health care providers about my test result?
We do recommend that you share this information with your health care providers. However, as explained by Maureen Smith, a researcher at Northwestern University, what you decide to do with your results is up to you.

Who will see my test results?
People who have access to your medical record will be able to see your genetic test result. This may include health professionals such as doctors, nurses, pharmacists, and genetic counselors. However, health professionals from other centers or hospitals will likely not have access to your results.

Should my other family members be tested?
If you are found to be at risk for a heritable genetic disease, your family may also be at risk. We discuss this further in the Family section.

Will this affect my health insurance?
No, your health insurance will not be affected by this test result. However, as discussed below by Maureen Smith, a researcher at Northwestern University, your life insurance and other areas may be affected.

Who can I contact if they have any more questions?
You can contact your local center, where you received the test. The Resources section also includes a lot of websites that we recommend.

Is it there a risk to my privacy?
Research that uses information from medical records and that involves genetic testing can affect your privacy. Your participation in this research will be held strictly confidential, and only coded numbers will be used to identify specimens and research records. While it is impossible to absolutely guarantee that information in our secure system will never be known by others, we are taking every possible precaution to see that this does not happen.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.

Resources

We are compiling a list of websites to help you understand genetics and genetic test results. If you would like to suggest other resources for this section, please feel free to This email address is being protected from spambots. You need JavaScript enabled to view it.!
INFORMATION ABOUT FAMILIAL ADENOMATOUS POLYPOSIS AND COLON CANCER:

Weblink to Cancer.Net FAP PagesCancer.Net
Direct link to the Familial Adenomatous Polyposis page at Cancer.Net. Very useful collection of resources and detailed information for patients with FAP, cancer, and their families


Weblink to Genetic and Rare Diseases Center (GARD)Genetic and Rare Diseases Center (GARD)
Supported by the NIH, this website has great resources for a huge range of genetic and rare disease. The above link is to their excellent Familial Adenomatous Polyposis resource. A link to the main GARD site is provided below as well.


Weblink to Genetics Home ReferenceGenetics Home Reference
Supported by the US National Library of Medicine/NIH, this is a great source of information for all things genetics. The above link is to their excellent Familial Adenomatous Polyposis resource. A link to the main site is provided below as well.


Weblink to Mayo Clinic's FAP resourceMayo Clinic Patient Care & Health Info
The Mayo Clinic have developed a major resource for health-related information and resources. The above link is to their Familial Adenomatous Polyposis webpage.


INFORMATION ABOUT GENETICS AND GENETIC TESTING:

Weblink to Genetics Home Reference Genetics Home Reference
Consumer-friendly information about the effects of genetic variations on human health. Federally-supported resources, include reviews of more than 800 genetic diseases and more than 1000 genes.


Weblink to NHGRI Learning ResourcesLearning Resources from the NHGRI
Lots of very good resources from the NHGRI, including major sections about The Human Genome Project, Facts Sheets, and educational resources for teachers and students.


Weblink to National Society of Genetic CounselorsFind a Genetic Counselor
The National Society of Genetic Counselors have a searchable database of genetic counselors. Their website also includes some education materials for patients and healthcare professionals.


Weblink to NHGRI Talking GlossaryNHGRI Talking Glossary
Talking glossary of genetic terms developed by the National Human Genome Research Institute. A huge range of definitions is provided by researchers from around the world.


Weblink to Help Me Understand GeneticsHelp Me Understand Genetics
Help Me Understand Genetics is a handbook from the National Institutes of Health that contain useful information about genetics in clear language and provides links to even more online resources. The entire handbook can also be downloaded as a pdf.


Weblink to the Genetic and Rare Diseases Information CenterGenetic and Rare Diseases Information Center (GARD)
A joint project from The Office of Rare Diseases Research (ORDR) and the National Human Genome Research Institute (NHGRI) that provides searchable information about genetic conditions and rare diseases. It also includes a list of FDA-Approved drugs and other medical products for treating rare disease.


Weblink to NORDNational Organization for Rare Disorders - Resources for Parents/Families
The National Organization for Rare Disorders (NORD) is a volunteer organization dedicated to empowering the rare disease community. Again, they have some very nice web resources.


Weblink to ELSIEthical, Legal and Social Implications Research Program
The ELSI Research Program supports examinations and investigations of the ethical, legal and social implications of genetics research.


Weblink to GINAGenetic Information Nondiscrimination Act of 2008
The Genetic Information Nondiscrimination Act of 2008, also referred to as GINA, is a new federal law that protects Americans from being treated unfairly because of differences in their DNA that may affect their health.


Weblink to Learn.GeneticsLearn.Genetics, University of Utah
Excellent resources, especially for those involved in education. Includes a catalog of animations, videos, interactive features, and virtual labs.


Weblink to the Dolan DNA Learning CenterDolan DNA Leaning Center
The DNALC provides genetics learning resources for teachers and students.


INFORMATION FOR RESEARCHERS:

Weblink to the ClinVar ACMG recommendations pageClinVar: ACMG Recommendations for Reporting of Incidental Findings in Clinical Exome and Genome Sequencing
Clinvar's dedicated ACMG page - a useful jumping-off point to the Genetic Testing Registry, OMIM, MedGen, and local ClinVar pages for each gene.


Weblink to GeneReviews APC-Associated Polyposis Conditions pageGeneReviews
KW Jasperson & RW Burt. GeneReviews: APC-Associated Polyposis Conditions (updated March, 2014).


Weblink to PubMed AbstractFamilial Adenomatous Polyposis
P Galiatsatos & WD Foulkes. The American Journal of Gastroenterology (2006) 101, 385–398.


Weblink to PubMed AbstractThe natural history of familial adenomatous polyposis syndrome: a 24 year review of a single center experience in screening, diagnosis, and outcomes.
RD Kennedy, DD Potter & M El-Youssef. Journal of Pediatric Surgery (2014) 49(1), 82-86.


Weblink to PubMed AbstractSystematic review of the impact of registration and screening on colorectal cancer incidence and mortality in familial adenomatous polyposis and Lynch syndrome
P Barrow et al. British Journal of Surgery (2013) 100(13), 1719-31.


About

What is the purpose of this information?
Our aim is to provide information about why we do genetic testing. We try to answer some common questions and offer guidance on some personal and practical issues. This information is for anybody with questions about genetic testing for any of the diseases and drugs listed in this site.

Are there geographical differences in testing, service or treatment?
Different centers have different policies in terms of how tests are administered and results shared. However, the results discussed in this document should be relevant to most individuals tested for risk of developing genetic disease.

How is this paid for?
If you received this test as part of the eMERGE research study, neither you nor your insurance company will have to pay anything toward this test

When was this content last updated?
June 28, 2016.

More Questions? The National Society of Genetic Counselors has developed a directory to help locate genetic counseling services near you.
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