GENE REFERENCE / HGNC:12403

TTN

titin

protein-coding gene2q31.2Gene information

What does this gene do?

The TTN gene provides instructions for making a very large protein called titin. This protein plays an important role in skeletal muscles, which the body uses for movement, and in heart (cardiac) muscle. Slightly different versions (called isoforms) of titin are made from the TTN gene in different muscles.

Within muscle cells, titin is an essential component of structures called sarcomeres. Sarcomeres are the basic units of muscle tensing (contraction); they are made of proteins that generate the mechanical force needed for muscles to contract. Titin has several functions within sarcomeres. One of the protein's main jobs is to provide structure, flexibility, and stability to these cell structures. Titin interacts with other muscle proteins, including actin and myosin, to keep the components of sarcomeres in place as muscles contract and relax. Titin also contains a spring-like region that allows muscles to stretch. Additionally, researchers have found that titin plays a role in chemical signaling and in assembling new sarcomeres.

Source: MedlinePlus, National Library of Medicine. Source publication: 2025-11-20. Source review: 2023-01.

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
dilated cardiomyopathy 1GMONDO:0011400 · Evaluated 2026-03-04	Autosomal dominant	DefinitiveDilated Cardiomyopathy Gene Curation Expert Panel
TTN-related myopathyMONDO:0100175 · Evaluated 2021-08-23	Autosomal recessive	DefinitiveCongenital Myopathies and Myasthenic Syndromes Gene Curation Expert Panel
arrhythmogenic right ventricular cardiomyopathyMONDO:0016587 · Evaluated 2025-10-28	Autosomal dominant	DisputedHereditary Cardiovascular Disease Gene Curation Expert Panel
myopathy, myofibrillar, 9, with early respiratory failureMONDO:0011362 · Evaluated 2025-06-23	Autosomal dominant	DefinitiveCongenital Myopathies and Myasthenic Syndromes Gene Curation Expert Panel
hypertrophic cardiomyopathyMONDO:0005045 · Evaluated 2025-10-28	Autosomal dominant	LimitedHereditary Cardiovascular Disease Gene Curation Expert Panel
TTN-related myopathy, dominant-negative TTNsvMONDO:1060225 · Evaluated 2026-02-23	Autosomal dominant	ModerateCongenital Myopathies and Myasthenic Syndromes Gene Curation Expert Panel
tibial muscular dystrophyMONDO:0010870 · Evaluated 2025-06-23	Autosomal dominant	ModerateCongenital Myopathies and Myasthenic Syndromes 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: 40,949
Submissions for variants in or overlapping this gene: 97,618
Submissions explicitly reporting this gene: 96,593
Alleles reported pathogenic / likely pathogenic: 6,155
VariationIDs with uncertain significance: 12,270
VariationIDs with conflicting classifications: 4,459

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 TTN?

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 6,155 alleles in TTN 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 TTN.

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

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