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TNNT2
troponin T2, cardiac type
The TNNT2 gene provides instructions for cardiac troponin T, a protein essential for the coordinated contraction of heart muscle cells, and is associated with various forms of inherited cardiomyopathy. TNNT2 encodes cardiac troponin T, a key component of the troponin complex found exclusively in heart muscle.
TNNT2 is located on the long (q) arm of chromosome 1, at band 1q32.1. Arm ratio per GRCh38 - banding schematic.
Explore chromosome 1 in the library →Overview
The TNNT2 gene, formally known as troponin T2, cardiac type, is responsible for producing cardiac troponin T (cTnT). This protein is found exclusively within the cells of the heart muscle and is a crucial component of the molecular machinery that enables the heart to beat effectively. The coordinated contraction and relaxation of cardiac muscle are fundamental for normal heart function.
Variants within the TNNT2 gene can disrupt the normal activity of cardiac troponin T, leading to impaired heart muscle function. Such disruptions are associated with a spectrum of inherited heart conditions, collectively known as cardiomyopathies.
What the gene does
The TNNT2 gene directs the synthesis of cardiac troponin T, a protein that is an integral part of the troponin complex. This complex, along with other proteins, forms the sarcomere, which is the basic functional unit responsible for muscle contraction within cardiac muscle cells. Within the sarcomere, thick and thin protein filaments interact in a dynamic process of binding and release, allowing them to slide past one another to facilitate muscle contraction.
Cardiac troponin T, as part of the troponin complex, helps to regulate the contraction cycle in response to calcium levels. When calcium levels are low, the troponin complex binds to the thin filaments, physically blocking the interaction required for muscle contraction between the thick and thin filaments. Conversely, an increase in intracellular calcium triggers structural changes within the troponin complex. This alteration unblocks the binding sites, permitting the thick and thin filaments to engage and initiate the muscle contraction process. The precise coordination facilitated by cardiac troponin T is vital for the heart's rhythmic pumping action.
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Chromosome location
The TNNT2 gene is situated on the long arm of chromosome 1, specifically at position 1q32.1. This precise genomic location ensures its organised presence within the human genome.
Protein structure
The TNNT2 gene encodes a protein composed of 298 amino acids. Structural analysis of cardiac troponin T reveals key regions that contribute to its function. These include two notable disordered regions. One disordered region is located at the N-terminus of the protein, spanning amino acids 1 to 95. Another disordered region is found between amino acids 120 and 219. These regions of structural flexibility are often important for protein-protein interactions and regulatory functions within the cellular environment.
Key variants
Variants within the TNNT2 gene can lead to alterations in the cardiac troponin T protein, potentially affecting its ability to regulate heart muscle contraction effectively. These genetic changes can range from single base pair substitutions to larger deletions or insertions within the gene sequence. The precise location and type of variant can influence the severity and presentation of associated heart conditions. Understanding these variants is crucial for diagnosing and managing inherited cardiomyopathies linked to TNNT2.
Sample of pathogenic variants
10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.
| Variant (HGVS) | Protein change | Classification | Evidence | Associated condition |
|---|---|---|---|---|
c.266T>A | p.Ile89Asn | Pathogenic | ★★☆☆ | Hypertrophic cardiomyopathy 2 |
c.274G>A | p.Gly92Arg | Pathogenic/Likely pathogenic | ★★☆☆ | Cardiomyopathy, familial restrictive, 3 |
c.287A>C | p.Asp96Ala | Pathogenic/Likely pathogenic | ★★☆☆ | Hypertrophic cardiomyopathy |
c.294T>G | p.Asp98Glu | Pathogenic/Likely pathogenic | ★★☆☆ | Primary dilated cardiomyopathy |
c.304C>T | p.Arg102Trp | Pathogenic | ★★☆☆ | not provided |
c.305G>A | p.Arg102Gln | Pathogenic/Likely pathogenic | ★★☆☆ | Hypertrophic cardiomyopathy 2 |
c.310C>T | p.Arg104Cys | Pathogenic/Likely pathogenic | ★★☆☆ | Cardiovascular phenotype |
c.358T>C | p.Phe120Leu | Pathogenic/Likely pathogenic | ★★☆☆ | TNNT2-related disorder |
c.360T>G | p.Phe120Leu | Pathogenic/Likely pathogenic | ★★☆☆ | Primary familial hypertrophic cardiomyopathy |
c.547C>T | p.Arg183Trp | Pathogenic/Likely pathogenic | ★★☆☆ | Cardiovascular phenotype |
Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.
Associated conditions
Pathogenic variants in the TNNT2 gene are associated with several inherited heart conditions, primarily various forms of cardiomyopathy. These include Familial restrictive cardiomyopathy, a condition where the heart muscle becomes stiff and loses its ability to fill with blood properly. TNNT2 variants are also linked to Nonsyndromic dilated cardiomyopathy, characterised by an enlarged and weakened heart muscle, and Nonsyndromic hypertrophic cardiomyopathy, where the heart muscle becomes abnormally thick.
No disease links recorded for this gene in our reference set.
Inheritance pattern
Conditions caused by pathogenic TNNT2 variants typically follow autosomal dominant inheritance.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
UK clinical status
In the UK, the TNNT2 gene is recognised on several NHS Genomic Medicine Service clinical panels, indicating its importance in diagnosing inherited cardiac conditions. It is included on panels for Dilated and arrhythmogenic cardiomyopathy (R132), Dilated Cardiomyopathy and conduction defects, Hypertrophic cardiomyopathy (R131), Left Ventricular Noncompaction Cardiomyopathy, and Paediatric or syndromic cardiomyopathy (R135). This inclusion signifies that TNNT2 is considered a gene for which testing is clinically indicated in appropriate patient groups within the NHS.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Diet & lifestyle considerations
Maintaining a heart-healthy lifestyle may be beneficial for individuals with TNNT2 variants, though it does not prevent the underlying genetic condition. General recommendations for cardiovascular health include regular, moderate physical activity, maintaining a balanced diet rich in fruits, vegetables, and whole grains, and limiting intake of saturated and trans fats, sodium, and refined sugars. Avoiding smoking and excessive alcohol consumption are also generally advised for supporting overall heart health. Any significant lifestyle changes should be discussed with a healthcare professional.
Supplement considerations
There is no conclusive evidence that specific dietary supplements can prevent, treat, or cure conditions associated with TNNT2 variants. While some supplements are marketed for cardiovascular health, their efficacy and safety for individuals with genetic heart conditions are generally not established through rigorous clinical trials. Individuals considering any supplements should consult with a healthcare provider to discuss potential benefits, risks, and interactions with other medications.
Frequently asked questions
What is the TNNT2 gene?
The TNNT2 gene provides instructions for making cardiac troponin T, a protein exclusively found in heart muscle. This protein is essential for regulating the contraction and relaxation of the heart.
What conditions are associated with TNNT2 gene variants?
Variants in the TNNT2 gene are associated with various inherited heart conditions, including Familial restrictive cardiomyopathy, Nonsyndromic dilated cardiomyopathy, and Nonsyndromic hypertrophic cardiomyopathy.
How does cardiac troponin T work in the heart?
Cardiac troponin T is part of the troponin complex, which regulates heart muscle contraction. It responds to calcium levels, allowing or blocking the interaction between muscle filaments to coordinate the heart's pumping action.
Is the TNNT2 gene tested in the NHS?
Yes, the TNNT2 gene is included on several NHS Genomic Medicine Service clinical panels for various cardiomyopathies, indicating its relevance for diagnostic testing in the UK.
Can lifestyle changes help manage TNNT2-related conditions?
While lifestyle changes cannot alter the genetic basis of TNNT2-related conditions, maintaining a heart-healthy lifestyle, including a balanced diet and regular exercise, may support overall cardiovascular health. Any significant changes should be discussed with a doctor.
References
- Marston SB. How do mutations in contractile proteins cause the primary familial cardiomyopathies? Journal of cardiovascular translational research. 2011. PMID: 21424860
- Otten E, Lekanne Dit Deprez RH, Weiss MM. Recurrent and founder mutations in the Netherlands: mutation p.K217del in troponin T2, causing dilated cardiomyopathy. Netherlands heart journal : monthly journal of the Netherlands Society of Cardiology and the Netherlands Heart Foundation. 2010. PMID: 20978592
- Rodríguez JE, McCudden CR, Willis MS. Familial hypertrophic cardiomyopathy: basic concepts and future molecular diagnostics. Clinical biochemistry. 2009. PMID: 19318019
- Hershberger RE, Pinto JR, Parks SB. Clinical and functional characterization of TNNT2 mutations identified in patients with dilated cardiomyopathy. Circulation. Cardiovascular genetics. 2009. PMID: 20031601
- Keren A, Syrris P, McKenna WJ. Hypertrophic cardiomyopathy: the genetic determinants of clinical disease expression. Nature clinical practice. Cardiovascular medicine. 2008. PMID: 18227814
- Gomes AV, Barnes JA, Harada K. Role of troponin T in disease. Molecular and cellular biochemistry. 2004. PMID: 15524172
- Bashyam MD, Savithri GR, Kumar MS. Molecular genetics of familial hypertrophic cardiomyopathy (FHC). Journal of human genetics. 2003. PMID: 12601548