Gene
TTN
titin
- HGNC 12403(opens in a new tab)
- Ensembl gene ENSG00000155657(opens in a new tab)
- NCBI Gene 7273(opens in a new tab)
Summary
- Cytogenetic location
- 2q31.2
- Coordinates
- Chromosome 2: 178,525,989–178,807,423 (GRCh38)
- Exons
- 363 exons across 281.4 kb
- Protein
- 35,991 amino acids
- Also known as
- CMPD4, FLJ32040, TMD, CMH9, LGMD2J, MYLK5
- Previous symbols
- CMD1G
- MANE Select transcript
- ENST00000589042.5NM_001267550.2
- Locus type
- gene with protein product
Reference genomeGRCh38hg38
Positions on gene and variant pages follow this choice, in this browser.
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Congenital Myopathies
- TTN-related myopathy
Skeletal muscle disorders caused by variants in TTN, which encodes the muscle protein titin, with onset from birth to adulthood.
- ClinGen rates the link definitive
- 4 GenCC submitters rate it definitive or strong
- On the ACMG secondary findings list
Dilated Cardiomyopathy
Enlargement and weakening of the left ventricle not explained by coronary artery or valve disease; inherited forms involve TTN, LMNA, RBM20, FLNC, BAG3, DSP, MYH7, TNNT2, DES, PLN and many other genes, and include Barth syndrome and the Emery-Dreifuss muscular dystrophies.
- ClinGen rates the link definitive
- 4 GenCC submitters rate it definitive or strong
- On the ACMG secondary findings list
What knowing changes
Knowing a genetic cause supports earlier heart monitoring and family screening, and for genes with a high arrhythmia risk such as LMNA, FLNC and RBM20 it informs decisions about rhythm monitoring and implantable defibrillators.
Distal Myopathies
- Distal myopathy
A group of inherited muscle disorders in which weakness starts in the hands, forearms, lower legs or feet, caused by genes such as TTN, DYSF, FLNC, MYH7, ADSS1, SMPX and MATR3.
- ClinGen rates the link definitive
- 2 GenCC submitters rate it definitive or strong
Limb-Girdle Muscular Dystrophy
Limb-girdle Muscular Dystrophy is defined as a collection of numerous subtypes with differing inheritance patterns (with diagnostic sufficiency being varied too). Carriers of variants related to the condition should seek guidance from a muscular-skeletal specialist for a definitive diagnosis.
- 1 GenCC submitter rates it definitive or strong
Myofibrillar Myopathies
- Myofibrillar myopathy
A group of muscle disorders in which the contractile structure of muscle fibers breaks down, caused by genes such as DES, CRYAB, MYOT, LDB3, FLNC and BAG3.
- ClinGen rates the link definitive
- 2 GenCC submitters rate it definitive or strong
What knowing changes
Because the heart is often involved, regular heart checks (such as ECG and echocardiography) are recommended even without symptoms.
How TTN is laid out
- Coding sequence
- Untranslated region
- Intron
- Direction of transcription
- Known disease-causing sites
- Stretches short reads find hard
- Variants with a page
Exons of the gene's MANE Select transcript (release v1.5), from NCBI and EMBL-EBI, on the GRCh38 reference genome.
Chromosome bands from UCSC's GRCh38 ideogram (2022-10-29).
Nearby genes from Ensembl release 116, on GRCh38.
Exons make up 109.2 kb of the gene's 281.4 kb; 107,976 of those bases code for the protein.
How a genome test reads TTN
4,747
positions in TTN where ClinVar classes a change as pathogenic or likely pathogenic
16 of them (0.3%) fall in regions short reads find hard.
- Low mappability (16 sites)Regions where 100 bp or 250 bp reads cannot be placed uniquely.
- Segmental duplications (6 sites)Copies of at least 1 kb sharing at least 90% identity with another part of the genome (paralogues, pseudogenes); reads may align to the wrong copy.
A whole genome covers all 281.4 kb of TTN, introns included, not only the 109.2 kb of exons.
Variants with a page (344)
The TTN variants with a page here, most review stars first. Each page describes ClinVar's public record of the variant, never a result.
| Variant | HGVS c. | Exon or intron | Position (GRCh38) | ClinVar classification | Review status |
|---|---|---|---|---|---|
| A2770Hfs*4 | c.8307_8308del | Exon 35 | 178,770,483 | Likely pathogenic | 2 stars out of 4 criteria provided, multiple submitters, no conflicts |
| A27689Lfs*31 | c.83064_83073del | Exon 326 | 178,563,058 | Likely pathogenic | 2 stars out of 4 criteria provided, multiple submitters, no conflicts |
| A28497Hfs*11 | c.85486del | Exon 326 | 178,560,645 | Likely pathogenic | 2 stars out of 4 criteria provided, multiple submitters, no conflicts |
| A35338Rfs*5 | c.106009_106010del | Exon 358 | 178,530,604 | Likely pathogenic | 2 stars out of 4 criteria provided, multiple submitters, no conflicts |
| A35544Pfs*2 | c.106629del | Exon 360 | 178,529,121 | Pathogenic/likely pathogenic | 2 stars out of 4 criteria provided, multiple submitters, no conflicts |
| c.669+2T>C | Intron 5 | 178,799,823 | Pathogenic/likely pathogenic | 2 stars out of 4 criteria provided, multiple submitters, no conflicts | |
| c.9163+1G>C | Intron 38 | 178,768,672 | Pathogenic | 2 stars out of 4 criteria provided, multiple submitters, no conflicts | |
| c.10303+2T>C | Intron 44 | 178,758,982 | Likely pathogenic | 2 stars out of 4 criteria provided, multiple submitters, no conflicts | |
| c.14093-1G>A | Intron 48 | 178,738,361 | Pathogenic | 2 stars out of 4 criteria provided, multiple submitters, no conflicts | |
| c.15496+1G>T | Intron 52 | 178,734,327 | Pathogenic | 2 stars out of 4 criteria provided, multiple submitters, no conflicts |
Traits linked to TTN
The Human Phenotype Ontology lists these as features of the rare conditions TTN can cause. Each trait's page lists the other genes linked to it.
Abnormality of the musculoskeletal system
- Centrally nucleated skeletal muscle fibers
- Difficulty running
- Difficulty walking up stairs
- Fatty replacement of skeletal muscle
- Generalized muscle weakness
- Increased variability in muscle fiber diameter
- Joint contracture
- Muscle tissue disease
Show 38 more traits
- Proximal neurogenic muscle weakness
- Tibialis anterior muscle atrophy
- Muscular dystrophy
- Ankle weakness
- Axial muscle weakness
- Decreased lung function due to weak breathing muscles
- Diffuse skeletal muscle wasting
- EMG: myopathic abnormalities
- Generalized decreased muscle tone
- Gowers sign
- Increased endomysial connective tissue
- Intermittent episodes of respiratory insufficiency due to muscle weakness
- Internally nucleated skeletal muscle fibers
- Limited hip movement
- Minicore myopathy
- Multiple joint contractures
- Muscle degeneration
- Muscle fiber degeneration
- Muscle fiber splitting
- Neck flexion weakness
- Necrotizing myopathy
- Poor head control
- Progressive muscle weakness
- Reduced spine movement
- Rimmed vacuoles
- Scoliosis
- Type 1 muscle fiber predominance
- Abnormal formation of the hip
- EMG abnormality
- EMG: decremental response of compound muscle action potential to repetitive nerve stimulation
- Hypertrophied muscle fibers
- Loss of fat tissue in localized area
- Prominent swayback
- Weakness of outermost muscles
- Absent muscle fiber merosin
- Frequent falls
- Myofibrillar myopathy
- Weak diaphragm
Abnormality of the cardiovascular system
- Abnormal heart rate
- Enlarged and thickened heart muscle
- Severely reduced left ventricular ejection fraction
- Stretched and thinned heart muscle
- Left ventricular systolic dysfunction
- Sudden cardiac death
- Cardiac failure
- Fainting spell
Show 14 more traits
- Palpitations
- Quivering upper heart chambers resulting in irregular heartbeat
- Abnormal heart valve morphology
- Atrioventricular reentrant tachycardia
- Heart attack
- Interruption of electrical communication between upper and lower chambers of heart
- Left ventricular hypertrophy
- Mitral valve prolapse
- Right ventricular failure
- Right ventricular hypertrophy
- Disease of the heart muscle
- Premature atrial contractions
- Reduced left ventricular ejection fraction
- Ventricular tachycardia
Abnormality of head or neck
- Weakness of facial musculature
- Bell's palsy
- High palate
- Limited neck flexibility
- Receding chin
- Abnormal facial shape
- Bifid uvula
- Big lower jaw
Show 4 more traits
External links
Gene records
Transcript
Protein
Where this comes from
- HGNC: the gene's symbol, name, other symbols and location.
- MANE Select v1.5, from NCBI and EMBL-EBI: the transcript, its exons and coding sequence.
- GenCC and ClinGen, released 2026-10-16: which conditions the gene is linked to, and how strongly.
- The ACMG secondary findings list, SF v3.2.
- ClinVar and the GIAB stratifications: known disease-causing sites, and the regions short reads find hard.
- The Human Phenotype Ontology, release 2026-09-01: the traits linked to the gene. Find out more at hpo.jax.org.
- Data release 2026.10.16-c6eea6bf.
Cite this page
Dante Labs. (n.d.). TTN gene: titin. Retrieved 16 October 2026, from https://dantelabs.com/genes/ttn
Dante Labs. TTN gene: titin [Internet]. [cited 16 October 2026]. Available from: https://dantelabs.com/genes/ttn
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