Traits

Traits linked to SCN2A

sodium voltage-gated channel alpha subunit 2

The Human Phenotype Ontology links 204 traits to SCN2A, by body system: features seen in people with one of the gene's rare conditions.

SCN2A

Abnormality of the nervous system

Trait	How often it is seen
Autism	Always
Bilateral tonic-clonic seizure with focal onset	Always
Cerebellar edema	Always
Delayed ability to stand	Always
Dystonia	Always
Encephalopathy	Always
Epilepsy	Always
Epileptic encephalopathy	Always
Episodic ataxia	Always
Fluid-filled sac located in membrane surrounding brain or spinal cord	Always
Generalized brain degeneration	Always
Grand mal seizures	Always
Hyperactive movements	Always
Intellectual disability, severe	Always
Repeated seizures without recovery between them	Always
Severe global developmental delay	Always
Tonic seizure	Always
Cognitive impairment	Very often (80–99%)
Episodic hemiplegia	Very often (80–99%)
Focal motor seizure	Very often (80–99%)
Generalized myoclonic seizure	Very often (80–99%)
Generalized-onset seizure	Very often (80–99%)
Global developmental delay	Very often (80–99%)
Hypsarrhythmia	Very often (80–99%)
Inability to walk	Very often (80–99%)
Infantile spasms	Very often (80–99%)
Intellectual disability	Very often (80–99%)
Jerking	Very often (80–99%)
Loss of developmental milestones	Very often (80–99%)
Multifocal epileptiform discharges	Very often (80–99%)
Neonatal seizure	Very often (80–99%)
Neurodevelopmental delay	Very often (80–99%)
Normal interictal EEG	Very often (80–99%)
Progressive gait ataxia	Very often (80–99%)
Seizure affecting one half of brain	Very often (80–99%)
Abnormal autonomic nervous system physiology	Often (30–79%)
Abnormality of the nervous system	Often (30–79%)
Anxiety	Often (30–79%)
Ataxia	Often (30–79%)
Atypical absence seizure	Often (30–79%)
Autism spectrum disorder	Often (30–79%)
Behavioral abnormality	Often (30–79%)
Brief seizures with staring spells	Often (30–79%)
Chorea	Often (30–79%)
Choreoathetosis	Often (30–79%)
Complex febrile seizure	Often (30–79%)
Degeneration of cerebrum	Often (30–79%)
Delayed speech and language development	Often (30–79%)
Difficulty sleeping	Often (30–79%)
EEG abnormality	Often (30–79%)
EEG with burst suppression	Often (30–79%)
EEG with focal spikes	Often (30–79%)
Epilepsia partialis continua	Often (30–79%)
Febrile seizure (within the age range of 3 months to 6 years)	Often (30–79%)
Focal aware seizure	Often (30–79%)
Focal clonic seizure	Often (30–79%)
Focal emotional seizure with laughing	Often (30–79%)
Focal hemiclonic seizure	Often (30–79%)
Focal impaired awareness autonomic seizure	Often (30–79%)
Focal impaired awareness seizure	Often (30–79%)
Focal tonic seizure	Often (30–79%)
Generalized clonic seizure	Often (30–79%)
Generalized tonic seizure	Often (30–79%)
Increased reflexes	Often (30–79%)
Interictal epileptiform activity	Often (30–79%)
Involuntary movements	Often (30–79%)
Involuntary writhing movements in fingers, hands, toes, and feet	Often (30–79%)
Lethargy	Often (30–79%)
Myoclonic seizure	Often (30–79%)
Obsessive-compulsive trait	Often (30–79%)
Parkinsonism	Often (30–79%)
Paroxysmal dyskinesia	Often (30–79%)
Photosensitive myoclonic seizure	Often (30–79%)
Photosensitive tonic-clonic seizure	Often (30–79%)
Slow movements	Often (30–79%)
Tetraparesis	Often (30–79%)
Abnormal corpus callosum morphology	Sometimes (5–29%)
Abnormal pyramidal sign	Sometimes (5–29%)
Absent reflexes	Sometimes (5–29%)
Action tremor	Sometimes (5–29%)
Aggressive behavior	Sometimes (5–29%)
Atypical absence status epilepticus	Sometimes (5–29%)
Balance impairment	Sometimes (5–29%)
Bulbar signs	Sometimes (5–29%)
Can't control feelings	Sometimes (5–29%)
Clonic seizure	Sometimes (5–29%)
Cortical dysplasia	Sometimes (5–29%)
Degeneration of cerebellum	Sometimes (5–29%)
Delayed myelination	Sometimes (5–29%)
Difficulty articulating speech	Sometimes (5–29%)
Diffuse cerebral atrophy	Sometimes (5–29%)
Diffuse white matter abnormalities	Sometimes (5–29%)
Disorder of involuntary muscle movements	Sometimes (5–29%)
Dysgenesis of the hippocampus	Sometimes (5–29%)
EEG with focal epileptiform discharges	Sometimes (5–29%)
EEG with generalized epileptiform discharges	Sometimes (5–29%)
EEG with spike-wave complexes	Sometimes (5–29%)
Epileptic spasm	Sometimes (5–29%)
Experiential epileptic aura	Sometimes (5–29%)
Eyelid myoclonia seizure	Sometimes (5–29%)
Fewer and broader ridges in brain	Sometimes (5–29%)
Focal head nodding automatism seizure	Sometimes (5–29%)
Generalized cerebral degeneration/underdevelopment	Sometimes (5–29%)
Headache	Sometimes (5–29%)
Impulsivity	Sometimes (5–29%)
Incoordination	Sometimes (5–29%)
Limb myoclonus	Sometimes (5–29%)
More active than typical	Sometimes (5–29%)
Neonatal electro-clinical seizure with behavior arrest	Sometimes (5–29%)
Poor fine motor coordination	Sometimes (5–29%)
Self-injurious behavior	Sometimes (5–29%)
Short attention span	Sometimes (5–29%)
Slurred speech	Sometimes (5–29%)
Status epilepticus without prominent motor symptoms	Sometimes (5–29%)
Sudden loss of muscle tone	Sometimes (5–29%)
Tremor	Sometimes (5–29%)
Underdevelopment of part of brain called corpus callosum	Sometimes (5–29%)
Uni- and bilateral multifocal epileptiform discharges	Sometimes (5–29%)
Worsening neurological symptoms	Sometimes (5–29%)
Continuous spike and waves during slow sleep	Rarely (1–4%)
Mental deterioration	Rarely (1–4%)
Simple febrile seizure	Rarely (1–4%)
Brain imaging abnormality	Not recorded
Psychomotor deterioration	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Abnormally small head	Often (30–79%)
Facial tics	Often (30–79%)
Limited neck range of motion	Often (30–79%)
Decreased facial muscle tone	Sometimes (5–29%)
Downturned corners of mouth	Sometimes (5–29%)
Drooling	Sometimes (5–29%)
Exaggerated cupid's bow	Sometimes (5–29%)
High forehead	Sometimes (5–29%)
Thin eyebrow	Sometimes (5–29%)
Cleft palate	Rarely (1–4%)
Depressed nasal bridge	Rarely (1–4%)
Nasal tip, upturned	Rarely (1–4%)
Sloping forehead	Rarely (1–4%)

Abnormality of the digestive system

Trait	How often it is seen
Vomiting	Always
Abnormality of the gastrointestinal tract	Very often (80–99%)
Gastrointestinal dysmotility	Very often (80–99%)
Abdominal bloating	Often (30–79%)
Anorexia	Often (30–79%)
Constipation	Often (30–79%)
Diarrhea	Often (30–79%)
Feeding difficulties	Often (30–79%)
Oral-pharyngeal dysphagia	Often (30–79%)
Poor suck	Often (30–79%)
Poor swallowing	Often (30–79%)
Nausea	Sometimes (5–29%)
Umbilical hernia	Rarely (1–4%)

Abnormality of the eye

Trait	How often it is seen
Involuntary, rapid, rhythmic eye movements	Always
Abnormal involuntary eye movements	Often (30–79%)
Dilated pupil	Often (30–79%)
Inward turning cross eyed	Often (30–79%)
Outward facing eye ball	Often (30–79%)
Ocular flutter	Sometimes (5–29%)
Oculomotor apraxia	Sometimes (5–29%)
Staring gaze	Sometimes (5–29%)
Visual impairment	Sometimes (5–29%)
Cross-eyed	Rarely (1–4%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Functional motor deficit	Very often (80–99%)
Cogwheel rigidity	Often (30–79%)
Decreased muscle tone in infant	Often (30–79%)
Low muscle tone	Often (30–79%)
Poor head control	Often (30–79%)
Rigidity	Often (30–79%)
Involuntary muscle stiffness, contraction, or spasm	Sometimes (5–29%)
Scoliosis	Sometimes (5–29%)
Spasticity and rigidity of muscles	Sometimes (5–29%)
Spastic tetraplegia	Not recorded

Abnormality of limbs

Trait	How often it is seen
Dropped arches	Sometimes (5–29%)
Limited knee straightening	Sometimes (5–29%)
Pes valgus	Sometimes (5–29%)
Skewfoot	Sometimes (5–29%)
Tibial torsion	Sometimes (5–29%)
Broad finger	Rarely (1–4%)
Short finger	Rarely (1–4%)
Talipes valgus	Rarely (1–4%)
Wide toe bones	Rarely (1–4%)

Abnormality of the integument

Trait	How often it is seen
Abnormal skin structure	Often (30–79%)
Flushing	Often (30–79%)
Paleness	Often (30–79%)
Blue discoloration of the skin	Sometimes (5–29%)
Cyanotic episode	Sometimes (5–29%)
Excessive sweating	Sometimes (5–29%)
Absent thumbnail	Rarely (1–4%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Abnormal T-wave	Sometimes (5–29%)
Aortopulmonary collateral arteries	Sometimes (5–29%)
Cardiac conduction abnormality	Sometimes (5–29%)
Abnormal heart rate	Rarely (1–4%)
Disease of the heart muscle	Rarely (1–4%)
Hole in heart wall separating two lower heart chambers	Rarely (1–4%)

Abnormality of the genitourinary system

Trait	How often it is seen
Renal dysplasia	Rarely (1–4%)
Short penis	Rarely (1–4%)
Ureterocele	Rarely (1–4%)

Abnormality of the respiratory system

Trait	How often it is seen
Apnea	Often (30–79%)
Aspiration	Sometimes (5–29%)
Breathing difficulties	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Dizziness	Always
Paroxysmal vertigo	Often (30–79%)

Abnormality of the endocrine system

Trait	How often it is seen
Early onset of puberty	Rarely (1–4%)

Abnormality of the immune system

Trait	How often it is seen
Recurrent respiratory infections	Often (30–79%)

Growth abnormality

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

Laboratory abnormality

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

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 SCN2A and how often each is seen. Find out more at hpo.jax.org.

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