Traits

Traits linked to MT-TV

mitochondrially encoded tRNA-Val (GUN)

The Human Phenotype Ontology links 74 traits to MT-TV, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of the nervous system

Trait	How often it is seen
Ataxia	Often (30–79%)
Chorea	Often (30–79%)
Disorder of involuntary muscle movements	Often (30–79%)
Dystonia	Often (30–79%)
Epilepsy	Often (30–79%)
Focal T2 hyperintense basal ganglia lesion	Often (30–79%)
Generalized myoclonic seizure	Often (30–79%)
Grand mal seizures	Often (30–79%)
Inability to coordinate movements when walking	Often (30–79%)
Nerve damage causing decreased feeling and movement	Often (30–79%)
Severe global developmental delay	Often (30–79%)
Abnormal prosody	Sometimes (5–29%)
Bulbar signs	Sometimes (5–29%)
Decreased reflex response	Sometimes (5–29%)
Demyelinating peripheral neuropathy	Sometimes (5–29%)
Increased reflexes	Sometimes (5–29%)
Infantile spasms	Sometimes (5–29%)
Loss of developmental milestones	Sometimes (5–29%)
Segmental peripheral demyelination/remyelination	Sometimes (5–29%)
Dementia	Not recorded
Encephalopathy	Not recorded
Migraine	Not recorded
Weakness of one side of body	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Cardiac conduction abnormality	Sometimes (5–29%)
Enlarged and thickened heart muscle	Sometimes (5–29%)
Stretched and thinned heart muscle	Sometimes (5–29%)
Abnormal heart rate	Not recorded
Abnormal left ventricular function	Not recorded
Cardiac failure	Not recorded
High blood pressure	Not recorded
Left ventricular hypertrophy	Not recorded
Stroke-like episode	Not recorded
Wolff-Parkinson-White syndrome	Not recorded

Laboratory abnormality

Trait	How often it is seen
Abnormality of Krebs cycle metabolism	Very often (80–99%)
Increased CSF lactate	Very often (80–99%)
High urine lactic acid levels	Often (30–79%)
Higher than normal levels of lactate in blood	Often (30–79%)
Fever	Sometimes (5–29%)
Hypothermia	Sometimes (5–29%)
Increased blood alanine	Sometimes (5–29%)
Decreased circulating citrulline concentration	Rarely (1–4%)
Diabetes mellitus	Not recorded
Increased lactate in body	Not recorded

Abnormality of the eye

Trait	How often it is seen
Pigmentary retinopathy	Often (30–79%)
Weakness of muscles controlling eye movement	Often (30–79%)
Involuntary, rapid, rhythmic eye movements	Sometimes (5–29%)
Optic atrophy	Sometimes (5–29%)
Rod-cone dystrophy	Sometimes (5–29%)
Cerebral visual impairment	Not recorded
Clouding of the lens of the eye at birth	Not recorded
Eye muscle paralysis	Not recorded
Hemianopia	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Decreased muscle tone in infant	Often (30–79%)
Involuntary muscle stiffness, contraction, or spasm	Often (30–79%)
Muscle weakness	Often (30–79%)
Spasticity and rigidity of muscles	Often (30–79%)
Mitochondrial myopathy	Sometimes (5–29%)
Ragged-red muscle fibers	Rarely (1–4%)
Muscle tissue disease	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Episodic vomiting	Often (30–79%)
Enlarged liver	Sometimes (5–29%)
Liver failure	Sometimes (5–29%)
Poor swallowing	Sometimes (5–29%)

Abnormality of the respiratory system

Trait	How often it is seen
Apnea	Sometimes (5–29%)
Breathing difficulty	Sometimes (5–29%)
Episodic difficulty breathing	Sometimes (5–29%)
Rapid breathing	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Sensorineural hearing impairment	Sometimes (5–29%)
Bilateral sensorineural hearing impairment	Not recorded
Progressive sensorineural hearing impairment	Not recorded

Abnormality of the genitourinary system

Trait	How often it is seen
Abnormal renal tubule morphology	Sometimes (5–29%)
Multiple glomerular cysts	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Faltering weight	Often (30–79%)
Growth abnormality	Not recorded

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 MT-TV and how often each is seen. Find out more at hpo.jax.org.

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