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Familial Hypertrophic Cardiomyopathy

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Overview

What is familial hypertrophic cardiomyopathy?
Familial hypertrophic cardiomyopathy (HCM) is an inherited condition where the heart muscle thickens and can disrupt blood flow from the heart. This thickening is most common in the interventricular septum, the muscle wall that separates the lower left chamber of the heart (left ventricle) from the right. In some, this can cause heartbeats to make an abnormal sound, or heart murmur. Most people with HCM no symptoms and have normal life expectancy. However, some people may have occasional chest pain, while others may feel their heart fluttering or pounding, or feel dizzy. A minority of people with familial HCM are at increased risk of heart failure and sudden death, and this risk can be reduced with appropriate health management. HCM affects about 1 person in every 200-500.

Changes in any of several genes are known to cause familial HCM. The following genes are all associated with familial HCM: MYH7, TPM1, MYBPC3, PRKAG2, TNNI3, MYL3, MYL2, and ACTC1.

If a person is found to have a genetic risk of developing familial HCM, they should be assessed for risk for sudden cardiac death (SCD), and these assessments should be repeated regularly. If a person with HCM is found to be at risk of sudden cardiac death, they may benefit from implantable cardioverter defibrillator therapy, which is discusses further under Treatment. Genetic testing can be offered to family members as well.

People with HCM or a genetic risk of HCM should also avoid competitive endurance training, activities involving sudden bursts (such as sprinting), heavy lifting, dehydration, and medications that affect pressure in the heart (e.g. ACE-inhibitors, angiotensin receptor blockers, and drugs that widen blood vessels).

For most people that have a genetic change related to familial HCM, there is a 50% chance each of their children will inherit this gene. A brother, sister, or parent of a person who has a familial HCM risk gene also has a 50% chance of inheriting this risk.

What is the genetic test?
Genetic testing allows us to identify people at risk for hypertrophic cardiomyopathy. Changes in several genes including MYH7, TPM1, MYBPC3, PRKAG2, TNNI3, MYL3, MYL2, and ACTC1 are known to cause the condition. Genetic testing allows us to identify people most at risk. The American College of Medical Genetics recommends testing and returning results for these genes. The genetic test can indicate if a person carries a genetic change associated with hypertrophic cardiomyopathy, as well as several other conditions discussed on this website.

How will this affect my health care?
When a person tests positive for a genetics risk for hypertrophic cardiomyopathy, it is recommended that they receive diagnosis and health management as soon as possible. Genetic testing can be offered to family members as well. Consulting with a clinical geneticist or genetic counselor can with health care decisions.

While HCM often has no symptoms and does not significantly impact life expectancy, there is a risk of sudden cardiac death, due to loss of heart function. For some, SCD is the first sign of the disease - especially younger people with HCM and competitive athletes. The primary concern for doctors, therefore, is to reduce the likelihood of SCD, and to intervene in those at high risk. The following factors are all important in assessing risk of SCD:

  • Family history of related heart problems/sudden death
  • A prior episode of sudden cardiac arrest
  • A prior episode of fainting/passing-out (syncope) caused by abnormal heart rhythms
  • Severe thickening of the heart muscle and a strong family history of SCD (causal and modifier genes)

None of these factors on their own are reliable predictors of SCD, but together they can paint a more complete picture of SCD risk. If the risk is considered to be high, implantable cardioverter defibrillator can be used - this is covered more fully under theTreatment tab. A range of medications are used to treat symptoms associated with HCM, and are also discussed under Treatment. Regular health checks - usually every 12-24 months - are necessary to assess SCD risk.

Who is at risk?
Hypertrophic cardiomyopathy is quite rare, and affects about 1 in 200-500 people. However, if a person’s mother or father has a change in a gene that is linked to familial hypertrophic cardiomyopathy, he or she has a 50% of inheriting this risk (i.e. a 1 in 2 chance). Similarly, if a person’s brother or sister has a familial hypertrophic cardiomyopathy risk gene, they will have a 50% risk of inheriting this risk. A person is also at increased risk if other relatives have HCM.

Does my ancestry affect my risk?
Several of the genetic risk factors associated with HCM may be more common in certain populations, but overall the prevalence seems to be similar worldwide. Men are more likely than women to develop the condition.

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

Treatment

A minority of people with HCM are at increased risk for sudden cardiac death and may benefit from an implantable cardioverter defibrillator (ICD). For those not at risk of SCD, regular risk assessment is important. No treatments currently exist to prevent or decrease disease development or to reverse HCM-related symptoms. However, symptoms can be managed by a range of medications and other treatments.

What are the treatments for hypertrophic cardiomyopathy?
No treatments currently exist to prevent or reverse HCM-related symptoms. However, symptoms can be managed by a range of medications and other treatments. A minority of people with HCM are at increased risk for sudden cardiac death (SCD) and may benefit from an implantable cardioverter defibrillator (ICD). Regular assessment and monitoring can help establish the need for ICD and other treatments options, discussed further below.

Health Monitoring In Those At-Risk
For people with HCM who do not currently meet criteria for an ICD for prevention, risk for SCD should be reassessed approximately every 12-24 months - or sooner if symptoms change

Healthy at-risk family members should have regular physical examination, echocardiography, and electrocardiogram (ECG). Echocardiography uses ultrasound waves to create pictures of the heart. Electrocardiogram (EKG or ECG) is a test that examines the electrical activity of the heart.
Guidelines reported by Cirino and Ho make the following recommendations about these screenings:

  • Patient is less than 12 years of age: Screening is optional unless ANY of the following are present: 1) family history of early HCM-related death, 2) early development of adverse complications such as left ventricular hypertrophy (LVH - where the left ventricle is thickened), 3) child is a competitive athlete or in an intense training program, 4) symptoms, or 5) other clinical findings that suggest early LVH.
  • Patient is 12-18 years old: Repeat evaluation every 12-18 months
  • patient is 18-21 years old, or older: Repeat evaluation at least every 5 years or if symptoms change. Repeat evaluations more frequently if the patient's family has late-onset LVH or HCM-related complications.



Agents/Circumstances to Avoid
People with HCM are advised to AVOID stressful physical activities:

  • Avoid competitive endurance training or participating in activities that require a level of intensity level similar to competitive athletics.
  • Avoid burst activities, like sprinting
  • Avoid heavy lifting
  • Avoid exercise in extreme conditions and maintain stay hydrated

To avoid symptoms from worsening, patients with outflow tract obstruction (i.e. obstructed ventricle) should be particularly careful in alcohol consumption; use Jacuzzis, steam rooms, and saunas. They shouls also AVOID the following:

  • Dehydration/decreased blood circulation (in particular, diuretics must be used with caution)
  • Medications that affect pressure in the heart (e.g. ACE-inhibitors, angiotensin receptor blockers, and drugs that widen blood vessels).)
  • Medications for erectile dysfunction (e.g., sildenafil, tadalafil)
Stimulant medications are considered with caution in children with HCM only after other treatment methods have been tried, and should be monitored carefully by a pediatric cardiologist.



Risk for Sudden Cardiac Death, and use of Implantable Cardioverter Defibrillator (ICD)
A minority of people with HCM are at an increased risk for sudden cardiac death (SCD) and may benefit from an ICD. An ICD is a small device placed in the heart, which delivers small electrical shocks. If a person requires an ICD, the device will be surgically placed under the skin near their collarbone, and then attached to the heart through small electrical cables. This will involve about two days in hospital. Several medications can be used to avoid problems with electrical activity that are delivered by an ICD.

To assess for risk factors associated with SCD, a doctor will usually look for evidence of two or more of the following.

  • Personal history of ventricular fibrillation (VF - a serious abnormality in heart rhythm), previous sudden death (resuscitated) or cardiac arrest, or sustained fast heart rhythms (ventricular tachycardia)
  • Family history of SCD
  • Extreme left ventricular hypertrophy, where the left ventricle is thickened (>30mm)
  • Low blood pressure after exercise
  • Recorded fast heart rhythms (non-sustained) after monitoring the heart across a 24-hour period or longer
  • Unexplained passing-out/fainting
In some circumstances, implantation of an ICD may be appropriate in the presence of a single risk factor.

Treatment of Symptoms
Treatment options include drug therapy, invasive septal reduction therapy (removing a small amount of muscle from the ventricular wall), and pacemakers. Heart transplantation may be necessary for patients who progress to advanced heart failure. The main medications are:

  • > Beta-blockers: Beta-blockers reduce heart rate and blood pressure, and affect electrical activity in the heart by changing how calcium is released in heart muscles.
  • L-type calcium channel blockers: are also used to regulate the electrical activity in the heart, and to maintain heart rhythms
  • Disopyramide: blocks sodium channels in the heart, which also helps regulate heart rhythms
  • A range of other drug treatments are available, and depend upon specific symptoms

Can treatments cause any problems?

  • Drug treatments can have several side effects, including low blood pressure, flushing, headache, dizziness, dry mouth, constipation, and nausea.
  • Placing an ICD in the body can be complicated, and the surgery to install the device can sometimes be life-threatening. Using an ICD can also be problematic. Two of the most common problems are 1) a low rate of appropriate shocks, which happens about 8% to 15% of the time, and 2) a high rate of inappropriate shocks, which happens about 20% to 30% of the time. Important steps to avoid experiencing problems with an ICD include avoiding competitive sports and limiting many other types of sporting activity.Anxiety is a common side-effect for people who had an ICD. In rare instances, ICDs can become infected.
  • Pacemakers can be painful and cause swelling, bruising, or bleeding after surgery. There is also an increased risk of blood clots and infection.

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?
Genetic testing tells us who is most at risk for hypertrophic cardiomyopathy. 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. Because people at risk for familial hypertrophic cardiomyopathy often do not have any symptoms early in life, it is important to know who is at risk in order to offer the chance of early health management.

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 developing familial hypertrophic cardiomyopathy. To do a genetic test, a medical professional will use your DNA to try to see if you have risk genes previously associated with hypertrophic cardiomyopathy.

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 familial hypertrophic cardiomyopathy, 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 familial hypertrophic cardiomyopathy. We also 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 local 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. These may include include increased monitoring of your health, including:

  • Examining your heart and physical health.
  • Taking a detailed family history of related problems
  • Family members may also be tested for risk.
  • Having regular heart checks
  • At a certain point, other treatments may be recommended (see the Treatment tab above)

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. 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. Familial hypertrophic cardiomyopathy 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. Familial hypertrophic cardiomyopathy is NOT inherited in this way.
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 family members could be affected?
If you have familial hypertrophic cardiomyopathy related to genetic changes, there is a 50% your child will have these genetic changes. For each of your brothers or sisters, there is also a 50% chance of having these genetic changes. Other family members are also at a much higher risk of having familial hypertrophic cardiomyopathy.

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. Health management can be effective in children at risk of familial hypertrophic cardiomyopathy before they reach 18 years of age.

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 of your life 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 HYPERTROPHIC CARDIOMYOPATHY:

Weblink to Children's Cardiomyopathy FoundationChildren's Cardiomyopathy Foundation
The Children's Cardiomyopathy Foundation (CCF) is a national, non-profit organization focused on pediatric cardiomyopathy. CCF is dedicated to accelerating the search for cures while improving diagnosis, treatment, and quality of life for children affected by cardiomyopathy


Cardiomyopathy UKCardiomyopathy UK
Cardiomyopathy UK is a charity providing support and information services, work to raise awareness of the condition, campaign for better access to quality treatment and promote research.


Weblink to Hypertrophic Cardiomyopathy FoundationHypertrophic Cardiomyopathy Foundation
The HCMA is dedicated to improving the lives of those with hypertrophic cardiomyopathy, HCM, preventing untimely deaths and advancing global understanding.


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


Weblink to Genetic and Rare Diseases Center (GARD) - Familial Hypertrophic Cardiomyopathy ResourcesGenetic 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 Familial Hypertrophic Cardiomyopathy resource. A link to the main GARD 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 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 Hypertrophic Cardiomyopathy GeneReviews pageGeneReviews
Cirino and Ho. GeneReviews: Hypertrophic Cardiomyopathy Overview (updated January, 2014).


Weblink to Hershberger et al. FDC ReviewHypertrophic cardiomyopathy: from genetics to treatment
AJ Marian. Circulation: European Journal of Clinical Investigation, 2010, April; 40(4): 360–369.


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?
December 30, 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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