Traits

Traits linked to SCN9A

sodium voltage-gated channel alpha subunit 9

The Human Phenotype Ontology links 131 traits to SCN9A, 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
Pain insensitivity	Always
Epilepsy	Very often (80–99%)
Generalized-onset seizure	Very often (80–99%)
Loss of developmental milestones	Very often (80–99%)
Peripheral neuropathy	Very often (80–99%)
Progressive gait ataxia	Very often (80–99%)
Seizure affecting one half of brain	Very often (80–99%)
Anxiety	Often (30–79%)
Atypical absence seizure	Often (30–79%)
Autism spectrum disorder	Often (30–79%)
Brief seizures with staring spells	Often (30–79%)
Cognitive impairment	Often (30–79%)
Complex febrile seizure	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 hemiclonic seizure	Often (30–79%)
Focal impaired awareness seizure	Often (30–79%)
Generalized clonic seizure	Often (30–79%)
Generalized myoclonic seizure	Often (30–79%)
Interictal epileptiform activity	Often (30–79%)
Jerking	Often (30–79%)
Multifocal epileptiform discharges	Often (30–79%)
Obsessive-compulsive trait	Often (30–79%)
Parkinsonism	Often (30–79%)
Photosensitive myoclonic seizure	Often (30–79%)
Photosensitive tonic-clonic seizure	Often (30–79%)
Slow movements	Often (30–79%)
Abnormal autonomic nervous system physiology	Sometimes (5–29%)
Action tremor	Sometimes (5–29%)
Ataxia	Sometimes (5–29%)
Atypical absence status epilepticus	Sometimes (5–29%)
Cortical dysplasia	Sometimes (5–29%)
Decreased sensation in extremities	Sometimes (5–29%)
Dysesthesia	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%)
Generalized brain degeneration	Sometimes (5–29%)
Generalized cerebral degeneration/underdevelopment	Sometimes (5–29%)
Grand mal seizures	Sometimes (5–29%)
Impulsivity	Sometimes (5–29%)
Incoordination	Sometimes (5–29%)
Poor fine motor coordination	Sometimes (5–29%)
Short attention span	Sometimes (5–29%)
Status epilepticus without prominent motor symptoms	Sometimes (5–29%)
Sudden loss of muscle tone	Sometimes (5–29%)
Generalized tonic seizure	Rarely (1–4%)
Repeated seizures without recovery between them	Rarely (1–4%)
Tremor	Rarely (1–4%)
Absent reflexes	Not recorded
Decreased nerve conduction velocity	Not recorded
Decreased number of peripheral myelinated nerve fibers	Not recorded
Decreased reflex response	Not recorded
Decreased sensory nerve conduction velocity	Not recorded
Impaired pain sensation	Not recorded

Abnormality of limbs

Trait	How often it is seen
Abnormality of the ankle	Very often (80–99%)
Abnormality of the knee	Very often (80–99%)
Foot acroosteolysis	Very often (80–99%)
Tapered finger	Very often (80–99%)
Decreased/absent ankle reflexes	Sometimes (5–29%)
Dropped arches	Sometimes (5–29%)
Fluid accumulation in lower limbs	Sometimes (5–29%)
Limited knee straightening	Sometimes (5–29%)
Pes valgus	Sometimes (5–29%)
Tibial torsion	Sometimes (5–29%)
Talipes valgus	Rarely (1–4%)
Autoamputation of digits	Not recorded
Breakdown of small bones of fingers	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Abnormal cortical bone morphology	Very often (80–99%)
Abnormal shape of end part of bone	Very often (80–99%)
Abnormality of the hip bone	Very often (80–99%)
Breakdown of bone	Very often (80–99%)
Low solidness and mass of the bones	Very often (80–99%)
Muscle degeneration	Very often (80–99%)
Prominent swayback	Very often (80–99%)
Cogwheel rigidity	Often (30–79%)
Rigidity	Often (30–79%)
Decreased muscle tone in infant	Sometimes (5–29%)
Low muscle tone	Sometimes (5–29%)
Generalized decreased muscle tone	Not recorded
Painless fractures due to injury	Not recorded

Abnormality of the integument

Trait	How often it is seen
Excessive sweating	Very often (80–99%)
Poor fingernail formation	Very often (80–99%)
Poor toenail formation	Very often (80–99%)
Itching	Often (30–79%)
Cyanotic episode	Sometimes (5–29%)
Paleness	Sometimes (5–29%)
Acral ulceration	Not recorded
Decreased ability to sweat	Not recorded
Flushing	Not recorded
Lack of sweating	Not recorded
Paronychia	Not recorded
Sporadic excessive sweating	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Extra bones within cranial sutures	Very often (80–99%)
Facial tics	Often (30–79%)
Limited neck range of motion	Often (30–79%)
Drooling	Sometimes (5–29%)
Decreased salivary flow	Not recorded
Decreased taste	Not recorded
Dry eye syndrome	Not recorded
Hyposmia	Not recorded
Lost smell	Not recorded
Lower jaw pain	Not recorded

Constitutional symptom

Trait	How often it is seen
Erythromelalgia	Very often (80–99%)
Allodynia	Sometimes (5–29%)
Anal pain	Not recorded
Jaw pain	Not recorded
Muscle ache	Not recorded
Pain	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Redness of skin or mucous membrane	Very often (80–99%)
Inflammation of blood vessel	Sometimes (5–29%)
Elevated heart rate	Not recorded
Palpitations	Not recorded
Slow heartbeats	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Constipation	Often (30–79%)
Acid reflux	Not recorded
Diarrhea	Not recorded
Feeding difficulties in infancy	Not recorded

Abnormality of the eye

Trait	How often it is seen
Abnormality of tear production	Not recorded
Blurred vision	Not recorded
Decreased corneal reflex	Not recorded
Eye pain	Not recorded

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Blood cancer	Sometimes (5–29%)
Platelet abnormalities	Sometimes (5–29%)

Laboratory abnormality

Trait	How often it is seen
Hypothermia	Sometimes (5–29%)
Laboratory abnormality	Not recorded

Abnormality of the genitourinary system

Trait	How often it is seen
Loss of bladder control	Not recorded

Abnormality of the immune system

Trait	How often it is seen
Recurrent respiratory infections	Sometimes (5–29%)

Abnormality of the respiratory system

Trait	How often it is seen
Runny Nose	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 SCN9A and how often each is seen. Find out more at hpo.jax.org.

One test. A lifetime of answers.

From $449Free shipping · Results in 6–8 weeks

Get my Genome Test