Traits

Traits linked to SV2A

synaptic vesicle glycoprotein 2A

The Human Phenotype Ontology links 24 traits to SV2A, 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
Elevated brain lactate level by MRS	Always
Global developmental delay	Always
Interictal EEG abnormality	Always
Loss of developmental milestones	Always
Reduced brain N-acetyl aspartate level by MRS	Always
Thin corpus callosum	Always
Tonic seizure	Always
Ventriculomegaly	Always
EEG with burst suppression	Often (30–79%)
Grand mal seizures	Often (30–79%)
Myoclonic seizure	Often (30–79%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Low muscle tone	Always
Opisthotonus	Often (30–79%)
Pigeon chest	Often (30–79%)

Growth abnormality

Trait	How often it is seen
Faltering weight	Always
Growth delay as children	Always
Prenatal growth deficiency	Often (30–79%)

Abnormality of head or neck

Trait	How often it is seen
Abnormally small head	Always
Highly arched eyebrow	Often (30–79%)

Abnormality of the eye

Trait	How often it is seen
Optic atrophy	Always
Cerebral visual impairment	Often (30–79%)

Abnormality of limbs

Trait	How often it is seen
Abnormal rhythmic movements of ankle	Often (30–79%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Low levels of amniotic fluid	Often (30–79%)

Abnormality of the digestive system

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

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 SV2A and how often each is seen. Find out more at hpo.jax.org.

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