Traits

Traits linked to TTN

titin

The Human Phenotype Ontology links 136 traits to TTN, by body system: features seen in people with one of the gene's rare conditions.

TTN

Abnormality of the musculoskeletal system

Trait	How often it is seen
Centrally nucleated skeletal muscle fibers	Always
Difficulty running	Always
Difficulty walking up stairs	Always
Fatty replacement of skeletal muscle	Always
Generalized muscle weakness	Always
Increased variability in muscle fiber diameter	Always
Joint contracture	Always
Muscle tissue disease	Always
Proximal neurogenic muscle weakness	Always
Tibialis anterior muscle atrophy	Always
Muscular dystrophy	Very often (80–99%)
Ankle weakness	Often (30–79%)
Axial muscle weakness	Often (30–79%)
Decreased lung function due to weak breathing muscles	Often (30–79%)
Diffuse skeletal muscle wasting	Often (30–79%)
EMG: myopathic abnormalities	Often (30–79%)
Generalized decreased muscle tone	Often (30–79%)
Gowers sign	Often (30–79%)
Increased endomysial connective tissue	Often (30–79%)
Intermittent episodes of respiratory insufficiency due to muscle weakness	Often (30–79%)
Internally nucleated skeletal muscle fibers	Often (30–79%)
Limited hip movement	Often (30–79%)
Minicore myopathy	Often (30–79%)
Multiple joint contractures	Often (30–79%)
Muscle degeneration	Often (30–79%)
Muscle fiber degeneration	Often (30–79%)
Muscle fiber splitting	Often (30–79%)
Neck flexion weakness	Often (30–79%)
Necrotizing myopathy	Often (30–79%)
Poor head control	Often (30–79%)
Progressive muscle weakness	Often (30–79%)
Reduced spine movement	Often (30–79%)
Rimmed vacuoles	Often (30–79%)
Scoliosis	Often (30–79%)
Type 1 muscle fiber predominance	Often (30–79%)
Abnormal formation of the hip	Sometimes (5–29%)
EMG abnormality	Sometimes (5–29%)
EMG: decremental response of compound muscle action potential to repetitive nerve stimulation	Sometimes (5–29%)
Hypertrophied muscle fibers	Sometimes (5–29%)
Loss of fat tissue in localized area	Sometimes (5–29%)
Prominent swayback	Sometimes (5–29%)
Weakness of outermost muscles	Sometimes (5–29%)
Absent muscle fiber merosin	Not recorded
Frequent falls	Not recorded
Myofibrillar myopathy	Not recorded
Weak diaphragm	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Abnormal heart rate	Always
Enlarged and thickened heart muscle	Always
Severely reduced left ventricular ejection fraction	Always
Stretched and thinned heart muscle	Always
Left ventricular systolic dysfunction	Very often (80–99%)
Sudden cardiac death	Very often (80–99%)
Cardiac failure	Often (30–79%)
Fainting spell	Often (30–79%)
Palpitations	Often (30–79%)
Quivering upper heart chambers resulting in irregular heartbeat	Often (30–79%)
Abnormal heart valve morphology	Sometimes (5–29%)
Atrioventricular reentrant tachycardia	Sometimes (5–29%)
Heart attack	Sometimes (5–29%)
Interruption of electrical communication between upper and lower chambers of heart	Sometimes (5–29%)
Left ventricular hypertrophy	Sometimes (5–29%)
Mitral valve prolapse	Sometimes (5–29%)
Right ventricular failure	Sometimes (5–29%)
Right ventricular hypertrophy	Sometimes (5–29%)
Disease of the heart muscle	Not recorded
Premature atrial contractions	Not recorded
Reduced left ventricular ejection fraction	Not recorded
Ventricular tachycardia	Not recorded

Abnormality of limbs

Trait	How often it is seen
Increased size of calf muscles	Always
Tibialis muscle weakness	Always
Foot drop	Often (30–79%)
Peroneal muscle atrophy	Often (30–79%)
Winged shoulder blade	Often (30–79%)
Club feet	Sometimes (5–29%)
Dropped arches	Sometimes (5–29%)
High-arched foot	Sometimes (5–29%)
Hip contracture	Sometimes (5–29%)
Long fingers	Sometimes (5–29%)
Proximal lower limb muscle weakness	Sometimes (5–29%)
Quadriceps weakness	Sometimes (5–29%)
Shortening of the achilles tendon	Sometimes (5–29%)
Distal upper limb muscle weakness	Rarely (1–4%)
Pelvic girdle muscle weakness	Not recorded
Weak shoulder muscles	Not recorded
Weakness of long finger extensor muscles	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Weakness of facial musculature	Always
Bell's palsy	Often (30–79%)
High palate	Often (30–79%)
Limited neck flexibility	Often (30–79%)
Receding chin	Often (30–79%)
Abnormal facial shape	Sometimes (5–29%)
Bifid uvula	Sometimes (5–29%)
Big lower jaw	Sometimes (5–29%)
Facial diplegia	Sometimes (5–29%)
Long face	Sometimes (5–29%)
Narrow mouth	Sometimes (5–29%)
Small retruded chin	Sometimes (5–29%)

Abnormality of the nervous system

Trait	How often it is seen
Motor delay	Always
Abnormal gait	Often (30–79%)
Delayed motor skills	Often (30–79%)
High pitched voice	Often (30–79%)
High stepping	Often (30–79%)
Waddling gait	Often (30–79%)
Absent reflexes	Sometimes (5–29%)
Clumsiness	Sometimes (5–29%)
Delayed speech and language development	Sometimes (5–29%)
Difficulty articulating speech	Sometimes (5–29%)
Intellectual disability, mild	Sometimes (5–29%)
Falls	Rarely (1–4%)

Abnormality of the respiratory system

Trait	How often it is seen
Breathing difficulty	Often (30–79%)
Exertional breathlessness	Often (30–79%)
Nocturnal hypoventilation	Often (30–79%)
Orthopnea	Often (30–79%)
Reduced vital capacity	Often (30–79%)
Respiratory function loss	Often (30–79%)
Stiff lung or chest wall causing decreased lung volume	Often (30–79%)
Respiratory failure	Not recorded

Laboratory abnormality

Trait	How often it is seen
Elevated blood creatine phosphokinase	Always
Fluid retention	Often (30–79%)
Increased muscle lipid content	Often (30–79%)
Mildly elevated creatine kinase	Often (30–79%)

Abnormality of the ear

Trait	How often it is seen
Dizziness	Often (30–79%)
Prominent ear	Sometimes (5–29%)
Sensorineural hearing impairment	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Drooping upper eyelid	Always
Eye muscle paralysis	Sometimes (5–29%)
Weakness of muscles controlling eye movement	Sometimes (5–29%)

Constitutional symptom

Trait	How often it is seen
Chest pain	Often (30–79%)
Decreased ability to exercise	Often (30–79%)
Fatigue	Often (30–79%)

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Thromboembolic stroke	Sometimes (5–29%)
Thromboembolism	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Faltering weight	Often (30–79%)
Short stature	Often (30–79%)

Abnormal cellular phenotype

Trait	How often it is seen
Mitochondrial depletion	Not recorded

Abnormality of the voice

Trait	How often it is seen
Inability to produce voice sounds	Sometimes (5–29%)

How often is among people with one of the gene's conditions, the most often across them, as the Human Phenotype Ontology records it. These pages describe traits and the research behind them; they are not a diagnosis, and a doctor or genetic counsellor is the person to ask about symptoms.

Where this comes from

The Human Phenotype Ontology, release 2026-09-01: the traits linked to TTN and how often each is seen. Find out more at hpo.jax.org.

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