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MYBPC3

Alias

CMD1MM; CMH4; FHC; LVNC10; MYBP-C

Associated disorders

The MYBPC3 gene is associated with autosomal dominant hypertrophic cardiomyopathy (HCM) (MedGen UID: 350526), dilated cardiomyopathy (DCM) (MedGen UID: 2880), and left ventricular noncompaction cardiomyopathy (LVNC) (MedGen UID: 349005).

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MYBPC3

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MYBPC3: Analysis includes the intronic variant NM_000256.3:c.3628-41_3628-17del25.


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Invitae tests that include this gene:

Pathogenic MYBPC3 variants are associated with 25% of clinical cases of HCM, <1% of DCM cases, and an unknown proportion of cases of LVNC.

The MYBPC3 gene encodes the protein myosin-binding protein C, cardiac-type. This protein is part of the sarcomere complex, which is present in both cardiac and skeletal muscle cells. The primary role of the sarcomere complex is muscle contraction. Pathogenic variants in genes that encode sarcomere proteins are a common cause of inherited cardiomyopathies.

OMIM: 600958

Clinical condition
The MYBPC3 gene is associated with autosomal dominant hypertrophic cardiomyopathy (HCM; MedGen UID: 350526), dilated cardiomyopathy (DCM; MedGen UID: 2880), and left ventricular noncompaction cardiomyopathy (LVNC; MedGen UID: 349005).

  • HCM is defined by the presence of unexplained left ventricular hypertrophy associated with non-dilated left ventricular chamber (PMID: 7594106).
  • DCM is defined by dilation and impaired contraction of the left or both ventricles (PMID: 10099905).
  • LVNC occurs when the ventricular wall does not finish the development process and retains a spongy or “trabeculated” appearance (PMID: 16567565).

These cardiomyopathies may lead to cardiac dysfunction, heart failure, arrhythmia, blood clots, or stroke (PMID: 24282766). Symptoms include palpitations, dizziness, syncope, chest pain, shortness of breath, fatigue, edema, and in some cases sudden cardiac arrest or death (SCA/D; PMID: 22068435, 22796258, 24998133).

Cardiomyopathy may develop at any age, and affected individuals may be asymptomatic until late in the course of the disease (PMID: 19254666).

Gene information
The MYBPC3 gene encodes the myosin-binding protein C (MyBP-C), which is part of the sarcomere complex of cardiac muscle cells. The primary role of the sarcomere complex is muscle contraction, within which MyBP-C supports the structure of the sarcomere filaments and regulates the speed of muscle contraction, although the mechanism is not fully understood (PMID: 19574547).

Inheritance
Pathogenic variants in MYBPC3 exhibit autosomal dominant inheritance. This means that an individual with a pathogenic variant has a 50% chance of passing that variant onto each of their offspring. MYBPC3 pathogenic variants exhibit reduced penetrance and variable expression, meaning that not everyone who inherits the pathogenic variant and a predisposition for disease will develop cardiomyopathy (PMID: 21787999).

Most cases of MYBPC3-related cardiomyopathy are inherited from a parent, but some cases occur spontaneously (i.e., an individual with a pathogenic variant has parents who do not have it; PMID: 22796258). Identification of a pathogenic variant allows for the recognition of at-risk relatives, who are recommended to pursue genetic testing (PMID: 29097296). Up to 5% of individuals with HCM have more than one pathogenic variant, which has been associated with an earlier and more severe clinical presentation (PMID: 16199542, 12707239, 21839045).

Management
Cardiomyopathy is recommended to be managed by a combination of lifestyle modification, medication, surgical and device therapy (pacemaker or implantable cardioverter defibrillator), and heart transplantation (PMID: 22068435, 29097296, 24282766). Cardiac surveillance through imaging (by echocardiogram and MRI) and electrocardiographic monitoring (by standard and ambulatory methods) are recommended upon diagnosis, at set intervals depending on age and presentation, and whenever symptoms present or worsen (PMID: 22068435, 19254666).

Pregnant women with DCM may be at risk for adverse effects, whereas women with HCM usually tolerate pregnancy without greatly increased risks (PMID: 24451172). There is little known about the effects of pregnancy in women with LVNC. Overall, women with cardiomyopathy who become pregnantare generally recommended to receive increased cardiac surveillance both for themselves and their fetus, genetic counseling, and an evaluation of treatment methods to weigh any risks to the pregnancy (PMID: 22068435, 24451172).

It is recommended that management decisions be made based on clinical presentation, symptoms, and family history, as well as appropriate SCA/D risk stratification (PMID: 22068435, 29097296, 19254666).

Genetic testing is recommended for at-risk family members of an individual with a disease-causing pathogenic variant (PMID: 29097296, 22068435, 19254666). Serial clinical screening by medical history, physical exam, echocardiogram, and ECG/EKG for at-risk family members is also recommended (PMID: 22068435, 21787999, 19254666).

Review date: February 2018

Assay and technical information

Invitae is a College of American Pathologists (CAP)-accredited and Clinical Laboratory Improvement Amendments (CLIA)-certified clinical diagnostic laboratory performing full-gene sequencing and deletion/duplication analysis using next-generation sequencing technology (NGS).

Our sequence analysis covers clinically important regions of each gene, including coding exons, +/- 10 base pairs of adjacent intronic sequence in the transcript listed below. In addition, analysis covers the select non-coding variants specifically defined in the table below. Any variants that fall outside these regions are not analyzed. Any specific limitations in the analysis of these genes are also listed in the table below.

Our analysis detects most intragenic deletions and duplications at single exon resolution. However, in rare situations, single-exon copy number events may not be analyzed due to inherent sequence properties or isolated reduction in data quality. If you are requesting the detection of a specific single-exon copy number variation, please contact Client Services before placing your order.

Gene Transcript reference Sequencing analysis Deletion/Duplication analysis
MYBPC3* NM_000256.3


*MYBPC3: Analysis includes the intronic variant NM_000256.3:c.3628-41_3628-17del25.