Traits

Traits linked to RARS2

arginyl-tRNA synthetase 2, mitochondrial

The Human Phenotype Ontology links 38 traits to RARS2, 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
Profound global developmental delay	Always
Brain degeneration	Often (30–79%)
Cerebellar vermis hypoplasia	Often (30–79%)
Decrease in size of the outer layer of the brain due to loss of brain cells	Often (30–79%)
Degeneration of cerebellum	Often (30–79%)
Generalized-onset seizure	Often (30–79%)
Lethargy	Often (30–79%)
Small cerebellum	Often (30–79%)
Absent speech development	Not recorded
Atrophy/Degeneration affecting the brainstem	Not recorded
Degeneration of cerebrum	Not recorded
Epilepsy	Not recorded
Increased reflexes	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Generalized decreased muscle tone	Always
Appendicular spasticity	Often (30–79%)
Elbow contracture	Often (30–79%)
Involuntary muscle stiffness, contraction, or spasm	Often (30–79%)
Low muscle tone in trunk	Often (30–79%)
Low muscle tone	Not recorded
Lower limb spasticity	Not recorded
Poor head control	Not recorded
Uncontrollable movement in upper arms	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Abnormally small head	Often (30–79%)
Narrow forehead	Not recorded
Narrow palate	Not recorded
Progressively abnormally small cranium	Not recorded
Prominent nasal bridge	Not recorded

Abnormal cellular phenotype

Trait	How often it is seen
Decreased activity of mitochondrial complex I	Often (30–79%)
Decreased activity of mitochondrial complex III	Often (30–79%)
Decreased activity of mitochondrial complex IV	Often (30–79%)

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Always
Acid reflux	Often (30–79%)
Poor suck	Often (30–79%)

Laboratory abnormality

Trait	How often it is seen
Higher than normal levels of lactate in blood	Often (30–79%)
Increased CSF lactate	Often (30–79%)

Abnormality of the eye

Trait	How often it is seen
Deeply set eye	Not recorded

Abnormality of the respiratory system

Trait	How often it is seen
Apnea	Often (30–79%)

Growth abnormality

Trait	How often it is seen
Faltering weight	Always

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 RARS2 and how often each is seen. Find out more at hpo.jax.org.

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