TTN

Chr 2ADAR

titin

Also known as: CMD1G, CMH9, CMPD4, CMYO5, CMYP5, EOMFC, HMERF, LGMD2J

The protein encoded by this gene is titin, a giant structural protein that spans half the length of a sarcomere and provides elasticity to striated muscle while serving as a template for assembly of contractile machinery. Mutations cause a spectrum of muscle diseases including hypertrophic and dilated cardiomyopathies, congenital myopathy with cardiomyopathy, limb-girdle muscular dystrophy, myofibrillar myopathy with early respiratory failure, and tibial muscular dystrophy. The disorders follow both autosomal dominant and autosomal recessive inheritance patterns, with pathogenicity resulting from disruption of sarcomere structure and muscle elasticity.

OMIMResearchSummary from RefSeq, OMIM, UniProt
LOFmechanismAD/ARLOEUF 0.356 OMIM phenotypes
Clinical SummaryTTN
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Gene-Disease Validity (ClinGen)
TTN-related myopathy · ARDefinitive

Definitive — sufficient evidence for diagnostic panels

6 total gene-disease associations curated

Population Constraint (gnomAD)
Constrained for loss-of-function variants (OE-LoF 0.33) despite low pLI — interpret in context.
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Clinical Trials
8 active or recruiting trials — potential therapeutic options may be available

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

Moderate LoF intolerance
LoF Constraint
0.35LOEUF
pLI 0.000
Z-score 22.76
OE 0.33 (0.300.35)
Moderately constrained

More LoF-intolerant than ~75% of genes

Missense Constraint
-1.10Z-score
OE missense 1.02 (1.011.04)
18060 obs / 17648.0 exp
Tolerant

Tolerant to missense variation

Observed / Expected Ratios
LoF OE0.33 (0.300.35)
00.351.4
Missense OE1.02 (1.011.04)
00.61.4
Synonymous OE1.00
01.21.6
LoF obs/exp: 435 / 1331.1Missense obs/exp: 18060 / 17648.0Syn Z: -0.17
Curated Mechanism (G2P)Gene2Phenotype (DDG2P) ↗
limitedTTN-related hypertrophic cardiomyopathyOTHERAD
limitedTTN-related arrhythmogenic right ventricular cardiomyopathyOTHERAD
definitiveTTN-related dilated cardiomyopathyOTHERAD
definitiveTTN-related titinopathy with arthrogryposis and/or myopathyLOFAR
DN
0.5575th %ile
GOF
0.5464th %ile
LOF
0.48top 25%

This gene has evidence for multiple mechanisms of pathogenicity (loss-of-function and dominant-negative). The Badonyi & Marsh model scores dominant-negative highest among its predictions, but genomic evidence (constraint, ClinVar variant spectrum, and literature) most strongly supports loss-of-function (haploinsufficiency). Different variants in this gene may act through different mechanisms — interpret in context of the specific variant.

LOF1 literature citation · LOEUF 0.35
DN1 literature citation

Literature Evidence

DNIn patient biopsies, NBR1 was localized abnormally diffusely in diseased muscle instead of being M band- and Z disc-associated, although in HMERF 50% of TK was expected to be wildtype. This suggested a dominant-negative mechanism of action for this mutation.PMID:15802564
LOFTruncated titin proteins and titin haploinsufficiency are targets for functional recovery in human cardiomyopathy due to TTN mutations.PMID:34731013

Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312. Mechanism ranking also informed by gnomAD constraint, ClinVar, and ClinGen data.

ClinVar Variant Classifications

0 submitted variants in ClinVar

Protein Context — Lollipop Plot

TTN · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

3D Protein StructureAlphaFold

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

Duchenne Muscular Dystrophy (DMD)Becker's Muscular Dystrophy (BMD)

Urinary Titin Biomarker in DMD

RECRUITING
NCT07332013Phase NAChildren's Hospital of PhiladelphiaStarted 2026-03-04
Descending stair walk
Cerebral Palsy (CP)

Spastic Myopathy in Adults With Cerebral Palsy

RECRUITING
NCT07293988Phase NANeurolocoStarted 2022-05-19
Guided Self-rehabilitation ContractConventional therapy group
CardiomyopathiesGenetic PredispositionCardiomyopathy, Primary

Biomarkers in SCOTland CardiomyopatHy Registry (Bio-SCOTCH)

RECRUITING
NCT06446271NHS Greater Glasgow and ClydeStarted 2024-06-26
Plasma biomarker levels
Inherited Non-Duchenne Myopathies

Clinical and Functional Assessment of Patients With Inherited Non-Duchenne Myopathies in Sohag University Hospital

RECRUITING
NCT06574919Sohag UniversityStarted 2024-08-01
Intracerebral HemorrhageAtrial Fibrillation

Anticoagulation in ICH Survivors for Stroke Prevention and Recovery

RECRUITING
NCT03907046Phase PHASE3Yale UniversityStarted 2020-01-28
ApixabanAspirin
Immune System Responses and Trained Immunity After AS01 AdministrationHealthy Adult

Improving Vaccine Protection for Older Adults

RECRUITING
NCT07527247Phase PHASE2Singapore General HospitalStarted 2025-11-06
AS01 adjuvant (0.5 mL intramuscular)YF17D (Stamaril, Sanofi-Pasteur)Placebo (NaCl 09%, 0.5mL)
Atrial FibrillationVentricular TachycardiaPremature Ventricular Contraction

Defining the Risk of Ventricular Tachycardia in Genetic Cardiomyopathies

RECRUITING
NCT06575881Vanderbilt University Medical CenterStarted 2023-12-13
Colon AdenocarcinomaStage IIA Colon Cancer AJCC v7Stage IIB Colon Cancer AJCC v7

Oxaliplatin, Leucovorin, and Fluorouracil With or Without Bevacizumab in Treating Patients Who Have Undergone Surgery for Stage II Colon Cancer

ACTIVE NOT RECRUITING
NCT00217737Phase PHASE3National Cancer Institute (NCI)Started 2005-09-06
BevacizumabFluorouracilLeucovorin
Clinical Literature
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