GENE REFERENCE / HGNC:11947

TNNI3

troponin I3, cardiac type

protein-coding gene19q13.42Gene information

What does this gene do?

The TNNI3 gene provides instructions for making a protein called cardiac troponin I, which is found solely in the heart (cardiac) muscle. Cardiac troponin I is one of three proteins that make up the troponin protein complex in cardiac muscle cells. The troponin complex is associated with a structure called the sarcomere, which is the basic unit of muscle contraction. Sarcomeres are made up of thick and thin filaments. The overlapping thick and thin filaments attach (bind) to each other and release, which allows the filaments to move relative to one another so that muscles can contract. The troponin complex, along with calcium, helps regulate tensing (contraction) of cardiac muscle.

For the heart to beat normally, cardiac muscle must contract and relax in a coordinated way. Cardiac troponin I helps to coordinate contraction of the heart. When calcium levels are low, the troponin complex binds to the thin filament. This binding blocks the interaction between the thick and thin filaments that is needed for muscle contraction. An increase in calcium levels causes structural changes in another troponin complex protein called troponin C, which then triggers the troponin complex to detach from the thin filament, allowing the heart muscle to contract.

Source: MedlinePlus, National Library of Medicine. Source publication: 2020-08-18. Source review: 2013-02.

ClinGen reviews

ClinGen reviews the evidence linking a particular gene to a condition. Each rating below describes the strength of that link. It does not classify a variant in your DNA file.

Condition	Inheritance	Evidence
arrhythmogenic right ventricular cardiomyopathyMONDO:0016587 · Evaluated 2019-07-16	Autosomal dominant	No Known Disease RelationshipArrhythmogenic Right Ventricular Cardiomyopathy Gene Curation Expert Panel
hypertrophic cardiomyopathyMONDO:0005045 · Evaluated 2017-09-05	Autosomal dominant	DefinitiveHypertrophic Cardiomyopathy Gene Curation Expert Panel
dilated cardiomyopathy 1FFMONDO:0013211 · Evaluated 2026-03-04	Autosomal dominant	StrongDilated Cardiomyopathy Gene Curation Expert Panel
dilated cardiomyopathy 2AMONDO:0012746 · Evaluated 2026-03-04	Autosomal recessive	StrongDilated Cardiomyopathy Gene Curation Expert Panel

ClinVar records

These numbers show what has been submitted to ClinVar. They cannot tell you how likely you are to have a condition.

Submitted alleles: 913
Submissions for variants in or overlapping this gene: 2,376
Submissions explicitly reporting this gene: 2,325
Alleles reported pathogenic / likely pathogenic: 83
VariationIDs with uncertain significance: 429
VariationIDs with conflicting classifications: 84

The rows count different things: alleles, submissions or VariationIDs. Their categories can overlap, so do not add them together. Pathogenic/likely pathogenic counts exclude structural variants that merely overlap a gene. A dash in the source means “not reported,” not zero.

NCBI produces the gene-summary file each week using counts recorded at the start of the month. The numbers may differ from those on the live ClinVar website. Read the field definitions ↗

View this gene in ClinVar ↗

YOUR DNA FILE

Can your DNA file tell you about TNNI3?

From a DNA test kit (such as 23andMe, AncestryDNA or MyHeritage). These kits check a fixed list of about 600,000 to 700,000 positions across your whole genome. ClinVar lists 83 alleles in TNNI3 reported as pathogenic or likely pathogenic. A kit checks only some of these positions, and often none of them.

From whole genome sequencing (a VCF file). Sequencing reads most of your genome. Your file lists the places where your DNA differs from the reference genome. Some regions are hard to sequence, including parts of some genes that have near-identical copies elsewhere, and a VCF file does not record which positions were read well.

If a variant is not in your file, that does not mean you don’t have it.

What BioDecode checks

BioDecode compares every variant in your file with ClinVar, on your own computer. For each match, it shows the ClinVar classification, the review status and the condition it was reported for. Your file is not uploaded.

A ClinVar classification applies to one particular variant and the condition it was reported for. It does not tell you about other variants in TNNI3.

BioDecode cannot fill gaps in your test, diagnose a condition or replace clinical testing.

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