Traits

Traits linked to NARS2

asparaginyl-tRNA synthetase 2, mitochondrial

The Human Phenotype Ontology links 59 traits to NARS2, 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
Difficulty articulating speech	Often (30–79%)
Epilepsy	Often (30–79%)
Intellectual disability, mild	Often (30–79%)
Mild global developmental delay	Often (30–79%)
Hypsarrhythmia	Sometimes (5–29%)
Peripheral neuropathy	Sometimes (5–29%)
Absent reflexes	Not recorded
Agenesis of corpus callosum	Not recorded
CNS hypomyelination	Not recorded
Decreased reflex response	Not recorded
Degeneration of cerebellum	Not recorded
Gliosis	Not recorded
Global developmental delay	Not recorded
Increased reflexes	Not recorded
Loss of brain cells	Not recorded
Loss of developmental milestones	Not recorded
Ongoing loss of nerve cells	Not recorded
Repeated seizures without recovery between them	Not recorded
Underdevelopment of part of brain called corpus callosum	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Ragged-red muscle fibers	Always
Low muscle tone in trunk	Often (30–79%)
Muscle degeneration	Often (30–79%)
Muscle weakness	Often (30–79%)
Proximal neurogenic muscle weakness	Often (30–79%)
Tired easily	Often (30–79%)
Generalized decreased muscle tone	Not recorded
Involuntary muscle stiffness, contraction, or spasm	Not recorded
Low muscle tone	Not recorded
Muscle tissue disease	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Weakness of facial musculature	Often (30–79%)
Downturned corners of mouth	Sometimes (5–29%)
Long philtrum	Sometimes (5–29%)
Nasal tip, upturned	Sometimes (5–29%)
Prominent metopic ridge	Sometimes (5–29%)
Short nose	Sometimes (5–29%)
Abnormally small head	Not recorded

Laboratory abnormality

Trait	How often it is seen
High blood sugar	Always
Elevated blood creatine phosphokinase	Often (30–79%)
Dehydration	Sometimes (5–29%)
Higher than normal levels of lactate in blood	Not recorded
Increased CSF lactate	Not recorded
Metabolic alkalosis	Not recorded

Abnormality of the eye

Trait	How often it is seen
Drooping upper eyelid	Often (30–79%)
Drooping of both upper eyelids	Sometimes (5–29%)
Cerebral visual impairment	Not recorded
Involuntary, rapid, rhythmic eye movements	Not recorded
Optic atrophy	Not recorded

Abnormality of the ear

Trait	How often it is seen
Bilateral sensorineural hearing impairment	Always
Thickened ears	Sometimes (5–29%)
Abnormal vestibular function	Rarely (1–4%)
Hearing impairment	Not recorded

Abnormal cellular phenotype

Trait	How often it is seen
Decreased activity of mitochondrial complex I	Always
Decreased activity of mitochondrial complex IV	Always

Abnormality of the digestive system

Trait	How often it is seen
Vomiting	Sometimes (5–29%)
Feeding difficulties	Not recorded

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Elevated hemoglobin A1c	Very often (80–99%)

Abnormality of limbs

Trait	How often it is seen
Curvature of ring finger	Sometimes (5–29%)

Abnormality of the genitourinary system

Trait	How often it is seen
Focal segmental glomerulosclerosis	Not recorded

Abnormality of the immune system

Trait	How often it is seen
Autoimmune antibody positivity	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 NARS2 and how often each is seen. Find out more at hpo.jax.org.

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