Traits

Traits linked to MT-ND2

mitochondrially encoded NADH:ubiquinone oxidoreductase core subunit 2

The Human Phenotype Ontology links 103 traits to MT-ND2, 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	Very often (80–99%)
Encephalopathy	Very often (80–99%)
Focal T2 hyperintense brainstem lesion	Very often (80–99%)
Global developmental delay	Very often (80–99%)
Lethargy	Very often (80–99%)
Leukodystrophy	Very often (80–99%)
Leukoencephalopathy	Very often (80–99%)
Poor eye contact	Very often (80–99%)
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%)
Peripheral neuropathy	Sometimes (5–29%)
Postural tremor	Sometimes (5–29%)
Segmental peripheral demyelination/remyelination	Sometimes (5–29%)
Peripheral nerve disease	Not recorded

Abnormality of the eye

Trait	How often it is seen
Cross-eyed	Very often (80–99%)
Damaged optic nerve	Very often (80–99%)
Drooping upper eyelid	Very often (80–99%)
Involuntary, rapid, rhythmic eye movements	Very often (80–99%)
Optic disc pallor	Very often (80–99%)
Paroxysmal involuntary eye movements	Very often (80–99%)
Slow decrease in sharpness of vision	Very often (80–99%)
Blind spot located at fixation point	Often (30–79%)
Blurred vision	Often (30–79%)
Centrocecal scotoma	Often (30–79%)
Optic atrophy	Often (30–79%)
Pigmentary retinopathy	Often (30–79%)
Progressive loss of vision	Often (30–79%)
Weakness of muscles controlling eye movement	Often (30–79%)
Abnormal color vision	Sometimes (5–29%)
Abnormal electroretinogram	Sometimes (5–29%)
Abnormality of visual evoked potentials	Sometimes (5–29%)
Blindness	Sometimes (5–29%)
Reduced contrast sensitivity	Sometimes (5–29%)
Retinal nerve fiber edema	Sometimes (5–29%)
Rod-cone dystrophy	Sometimes (5–29%)
Leber optic atrophy	Not recorded
Visual loss	Not recorded

Laboratory abnormality

Trait	How often it is seen
Abnormality of Krebs cycle metabolism	Very often (80–99%)
Increased circulating pyruvate concentration	Very often (80–99%)
Increased CSF lactate	Very often (80–99%)
Increased lactate in body	Very often (80–99%)
Low blood sugar	Very often (80–99%)
High urine lactic acid levels	Often (30–79%)
Higher than normal levels of lactate in blood	Often (30–79%)
Diabetes mellitus	Sometimes (5–29%)
Fever	Sometimes (5–29%)
Hypothermia	Sometimes (5–29%)
Increased blood alanine	Sometimes (5–29%)
Decreased circulating citrulline concentration	Rarely (1–4%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Low muscle tone	Very often (80–99%)
Mitochondrial myopathy	Very often (80–99%)
Muscle weakness	Very often (80–99%)
Poor head control	Very often (80–99%)
Decreased muscle tone in infant	Often (30–79%)
Involuntary muscle stiffness, contraction, or spasm	Often (30–79%)
Spasticity and rigidity of muscles	Often (30–79%)
Muscle tissue disease	Sometimes (5–29%)
Ragged-red muscle fibers	Rarely (1–4%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Enlarged and thickened heart muscle	Very often (80–99%)
Retinal telangiectasia	Often (30–79%)
Retinal vascular tortuosity	Often (30–79%)
Abnormal heart rate	Sometimes (5–29%)
Cardiac conduction abnormality	Sometimes (5–29%)
Stretched and thinned heart muscle	Sometimes (5–29%)
Ventricular preexcitation	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Enlarged liver	Very often (80–99%)
Vomiting	Very often (80–99%)
Episodic vomiting	Often (30–79%)
Feeding difficulties	Sometimes (5–29%)
Liver failure	Sometimes (5–29%)
Poor swallowing	Sometimes (5–29%)

Abnormality of the respiratory system

Trait	How often it is seen
Respiratory function loss	Very often (80–99%)
Apnea	Sometimes (5–29%)
Breathing difficulty	Sometimes (5–29%)
Episodic difficulty breathing	Sometimes (5–29%)
Rapid breathing	Sometimes (5–29%)

Abnormal cellular phenotype

Trait	How often it is seen
Decreased activity of mitochondrial complex I	Always
Abnormal mitochondria in muscle tissue	Very often (80–99%)
Mitochondrial respiratory chain defects	Very often (80–99%)

Abnormality of the genitourinary system

Trait	How often it is seen
Proximal tubulopathy	Very often (80–99%)
Abnormal renal tubule morphology	Sometimes (5–29%)
Multiple glomerular cysts	Sometimes (5–29%)

Abnormality of head or neck

Trait	How often it is seen
Abnormally small head	Sometimes (5–29%)
Central retinal vessel vascular tortuosity	Not recorded

Growth abnormality

Trait	How often it is seen
Faltering weight	Very often (80–99%)
Prenatal growth deficiency	Very often (80–99%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Fetal distress	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Sensorineural hearing impairment	Very often (80–99%)

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-ND2 and how often each is seen. Find out more at hpo.jax.org.

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