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Familial Medullary Thyroid Carcinoma (FMTC)

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Overview

NOTE: Link to Multiple Endocrine Neoplasia Type 2 ALSO

What is Familial Medullary Thyroid Carcinoma (FMTC)? Familial Medullary Thyroid Carcinoma (FMTC) is one of a group of disorders that affect the endocrine system - a network of glands in the body involved in making hormones. FMTC is part of a larger group of disorders called Multiple Endocrine Neoplasia Type 2 (MEN2), which are very rare, affecting about 1 in 30,000 people.

Glands that make up the endocrine system are located around the body, including the pineal and pituitary glands (in the brain), adrenal gland (near the kidneys), thyroid gland (neck), thymus (near the heart), pancreas (near the stomach), and ovary (women)/testis (men) (reproductive system). Unlike other forms of MEN2, FMTC affects only the thyroid, where tumors, or growths, can develop into cancers and become life-threatening. The can also spread to other organs in the body.

FMTC is caused by a fault in a gene called the RET proto-oncogene, or simply RET, which can be identified by genetic testing. If a person is found to have a copy of RET linked to FMTC, but have not yet developed the disease, a thyroidectomy is typically performed. This involves removing the thyoid gland and lymph nodes, and sometimes the nearby parathyroid gland. Young children usually wait until they are 5-10 years of age before having this surgery. People at risk for FMTC, who are 10 years of age or older, usually have a thyroidectomy very soon after the test result. If untreated, those with a genetic risk for FMTC are at a high risk of developing medullary thyroid cancer.

After surgery, blood tests and scans can be carried out to look for cancer or for an abnormal growth called C-cell hyperplasia that leads to too much of a hormone called calcitonin. If calcitonin levels are still high, this indicates that the cancer has spread, and further surgery or treatments will be needed. However, if the C-cell hyperplasia or cancer was contained within the thyroid, and calcitonin levels are normal, a patients is considered cured.

Even where the patient is cured, they will need to continue to take a drug called Levothyroxine, which replaces hormones produced by thyroid. For many of the changes in the RET gene associated with FMTC, the risk of medullary thyroid cancer can approach 100%. However, early intervention can reduce this risk significantly. Source: Machens et al. 2003 (see Resources). Image created by Iconarray.com. Risk Science Center and Center for Bioethics and Social Sciences in Medicine, University of Michigan. Accessed 2017-01-20.

What is the genetic test?
Mutations in a gene called RET have been shown to cause FMTC. Genetic testing allows us to identify people at risk of developing the condition. There is a large risk (up to 100%) that people with known genetic risk factors in RET will develop thyroid cancer, often at a young age (less that 40 years old). Early identification of FMTC risk allows us to begin treatment at a young age. Usually, this involves removing that thryroid, and significantly reduces the risk of cancer.

How will this affect my health care?
If a person is found to a genetic risk of developing FMTC, a thyroidectomy is typically performed. A thyroidectomy involves removing the thyoid gland and lymph nodes. Sometimes the nearby parathyroid gland is removed too. Young children usually wait until they are 5-10 years of age before having this surgery. People at risk for FMTC, who are 10 years of age or older, usually have a thyroidectomy very soon after the test result. If untreated, those with a genetic risk for FMTC are at a high risk of developing medullary thyroid cancer.

After surgery, blood tests and scans will look for cancer or for an abnormal growth called C-cell hyperplasia - discussed further under Treatment. Even where further treatment is not needed, patients will need to a drug called Levothyroxine to replace thyroid hormones - again see Treatment for more details.

Who is at risk?
Medullary thyroid carcinoma develops in about 1 in 14,000 people. However, if a person’s mother or father has a change in the gene that is linked to FMTC, he or she has a 50% of inheriting this risk (i.e. a 1 in 2 chance). Similarly, if a person’s brother, sister has FMTC or risk gene, they will have a 50% risk of inheriting this risk. If a person's other relatives have FMTC, they are also at increased risk of developing the condition.

Does my ancestry affect my risk?
There is no strong evidence linking FMTC with ancestry.

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

Treatment

Treatment

What are the treatments for FMTC?
Blood tests are used to check hormone levels, and scans of the neck check for tumor growths. If a growth is found a thyroidectomy is recommended to remove the thyroid.

Even where there is no evidence for abnormalities in the thyroid, a thyroidectomy is often recommended for patients with a genetic risk of developing FMTC. Young children typically should wait until they are 5-10 years of age before having this surgery (although in certain circumstances, it may be recommended in children under 5 years). People with the RET risk gene who are 10 years of age or older, typically have a thyroidectomy very soon after the test result. If untreated, those with a genetic risk for FMTC are at a high risk of developing medullary thyroid cancer.

After surgery, blood tests and scans can be carried out to look for cancer or for an abnormal growth called C-cell hyperplasia that leads to too much of a hormone called calcitonin. If calcitonin levels are still high, this indicates that the cancer has spread, and further surgery or treatments will be needed. However, if the C-cell hyperplasia or cancer was contained within the thyroid, and calcitonin levels are normal, a patients is considered cured.

Even where the patient is cured, they will need to continue to take a drug called Levothyroxine, which replaces hormones produced by thyroid.

If identified late, surgery may not be an option for some FMTC patients. In this case, treatment options may involve a form of radioactive therapy - i.e. treatment with radiation. Radiation can destroy the thyroid gland and any other thyroid cells, with little effect on the rest of your body. It may be repeated at 3-6 months intervals.

Can treatments cause any problems?
For thyroidectomy, a common problem is hypothyroidism, where the thyroid does not produce enough hormone. This problem can be managed by taking the drug Levothyroxine. Other problems are bleeding and blocked airways. Rare problems include infection after surgery, damaged nerves in the neck, and a hoarse voice that may be permanent.

For radioactive therapy, nausea us quite common, and vomiting may also be an issue. and occasionally vomiting. Diarrhea, flushes, and bone pain are also problems.

Levothyroxine can cause sweating, anxiety, nausea, and other problems. Doses of Levothyroxine that are too high can lead to heart palpitations, nausea, stomach pain, anxiety, and a range of other side effects. Allergic reactions can cause breathing difficulties and swelling, especially to the tongue and face.

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?
People are at risk of developing FMTC because they inherit a faulty gene that causes it. Genetic testing tells us who is most at risk for developing the condition. 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 FMTC. All genetic tests look at your DNA to try to identify faulty genes previously associated with FMTC.

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 FMTC, 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.

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 FMTC. 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, and/or that you are a carrier. 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/or you may be a carrier. 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. FMTC 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. FMTC is NOT a recessive condition.
Please note that the Resources section provides links to a number of websites that provide a more detailed explanation of inheritance. Learn.Genetics at the University of Utah have an 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 FMTC, there is a 50% your child will too. Other family members are also at a much higher risk of having FMTC.

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, including FMTC. Early treatment to fight FMTC is possible in children of five years of age, or sometimes younger, and testing is appropriate to guide treatment.

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 FMTC AND CANCER:

Weblink to AMEND Patient Information BookletAMEND
Patient Information Booklet on FMTC - Excellent Resource from the Association for Multiple Endocrine Neoplasia Disorders (AMEND), UK


Weblink to You and Your Hormones Patient InformationYou and Your Hormones
Familial medullary thyroid cancer Patient resource from the Society of Endocrinology, UK. Includes links to other endocrine conditions.


Weblink to Cancer.Net MEN2 PagesCancer.Net
Direct link to the Multiple Endocrine Neoplasia Type 2 disorders resource at Cancer.Net. Very useful collection of resources and detailed information for patients with MEN2 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 diseases. The above link is to their MEN2 resource. A link to the main GARD site is provided below as well.


Weblink to Genetics Home ReferenceGenetics Home Reference
Extensive resource about rare and genetic and genetic diseases. The above link leads to their excellent MEN2 pages. A link to the main site is provided below as well.


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 Learning Resources from the NHGRILearning 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 Dolan DNA Learning Center (DNALC) provides genetics learning resources for teachers and students - includes large repository of animations, photos, and text articles.


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 MEN2 pageGeneReviews
Marquard & Charis. GeneReviews: Multiple Endocrine Neoplasia Type 2 (updated June, 2015), includes resources on FMTC, as well as sub-types 2A and 2B.


Weblink to machens et al. NEJMEarly malignant progression of hereditary medullary thyroid cancer
Machens et al., 2003. These data provide initial guidelines for the timing of prophylactic thyroidectomy in asymptomatic carriers of RET gene mutations.


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?
January 23, 2017.

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