Traits

Traits linked to KCNA1

potassium voltage-gated channel subfamily A member 1

The Human Phenotype Ontology links 105 traits to KCNA1, by body system: features seen in people with one of the gene's rare conditions.

KCNA1

Abnormality of the nervous system

Trait	How often it is seen
Epilepsy	Always
Abnormality of movement	Very often (80–99%)
Balance impairment	Very often (80–99%)
Chorea	Very often (80–99%)
Disorder of involuntary muscle movements	Very often (80–99%)
Dystonia	Very often (80–99%)
Epileptic encephalopathy	Very often (80–99%)
Focal motor seizure	Very often (80–99%)
Generalized myoclonic seizure	Very often (80–99%)
Global developmental delay	Very often (80–99%)
Incoordination	Very often (80–99%)
Intellectual disability	Very often (80–99%)
Involuntary movements	Very often (80–99%)
Involuntary writhing movements in fingers, hands, toes, and feet	Very often (80–99%)
Myokymia	Very often (80–99%)
Ataxia	Often (30–79%)
Clumsiness	Often (30–79%)
Difficulty articulating speech	Often (30–79%)
Difficulty sleeping	Often (30–79%)
EEG abnormality	Often (30–79%)
EEG with burst suppression	Often (30–79%)
Focal sensory seizure	Often (30–79%)
Focal tonic seizure	Often (30–79%)
Headache	Often (30–79%)
Hypsarrhythmia	Often (30–79%)
Increased reflexes	Often (30–79%)
Lethargy	Often (30–79%)
Slurred speech	Often (30–79%)
Autism spectrum disorder	Sometimes (5–29%)
Brief seizures with staring spells	Sometimes (5–29%)
Choreoathetosis	Sometimes (5–29%)
Degeneration of cerebellum	Sometimes (5–29%)
Delayed myelination	Sometimes (5–29%)
Delayed speech and language development	Sometimes (5–29%)
Diffuse cerebral atrophy	Sometimes (5–29%)
Diffuse white matter abnormalities	Sometimes (5–29%)
EEG with spike-wave complexes	Sometimes (5–29%)
Episodic ataxia	Sometimes (5–29%)
Febrile seizure (within the age range of 3 months to 6 years)	Sometimes (5–29%)
Fewer and broader ridges in brain	Sometimes (5–29%)
Generalized clonic seizure	Sometimes (5–29%)
Generalized tonic seizure	Sometimes (5–29%)
Grand mal seizures	Sometimes (5–29%)
Infantile spasms	Sometimes (5–29%)
Jerking	Sometimes (5–29%)
Loss of developmental milestones	Sometimes (5–29%)
Migraine	Sometimes (5–29%)
More active than typical	Sometimes (5–29%)
Motor delay	Sometimes (5–29%)
Seizure affecting one half of brain	Sometimes (5–29%)
Self-injurious behavior	Sometimes (5–29%)
Specific learning disability	Sometimes (5–29%)
Sudden loss of muscle tone	Sometimes (5–29%)
Toe walking	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%)
Writer's cramp	Sometimes (5–29%)
Babinski sign	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
EMG abnormality	Very often (80–99%)
Spastic walk	Very often (80–99%)
Type 1 muscle fiber predominance	Very often (80–99%)
Decreased muscle tone in infant	Often (30–79%)
Muscle spasm	Often (30–79%)
Muscle stiffness	Often (30–79%)
Poor head control	Often (30–79%)
Congenital diaphragmatic hernia	Sometimes (5–29%)
Involuntary muscle stiffness, contraction, or spasm	Sometimes (5–29%)
Kyphoscoliosis	Sometimes (5–29%)
Myotonia	Sometimes (5–29%)
Scoliosis	Sometimes (5–29%)
Spasticity and rigidity of muscles	Sometimes (5–29%)
Muscular abnormality	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Craniofacial disproportion	Sometimes (5–29%)
Abnormally small head	Rarely (1–4%)
Cleft palate	Rarely (1–4%)
Depressed nasal bridge	Rarely (1–4%)
Nasal tip, upturned	Rarely (1–4%)
Sloping forehead	Rarely (1–4%)

Abnormality of limbs

Trait	How often it is seen
Hand clenching	Sometimes (5–29%)
Increased size of calf muscles	Sometimes (5–29%)
Broad finger	Rarely (1–4%)
Short finger	Rarely (1–4%)
Wide toe bones	Rarely (1–4%)
Abnormality of the hand	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Often (30–79%)
Nausea	Often (30–79%)
Poor suck	Often (30–79%)
Poor swallowing	Often (30–79%)
Umbilical hernia	Rarely (1–4%)

Abnormality of the eye

Trait	How often it is seen
Blurred vision	Often (30–79%)
Double vision	Often (30–79%)
Cross-eyed	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 integument

Trait	How often it is seen
Excessive sweating	Often (30–79%)
Absent thumbnail	Rarely (1–4%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Hole in heart wall separating two lower heart chambers	Rarely (1–4%)

Abnormality of the ear

Trait	How often it is seen
Dizziness	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%)

Abnormality of the respiratory system

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

Growth abnormality

Trait	How often it is seen
Faltering weight	Rarely (1–4%)

Laboratory abnormality

Trait	How often it is seen
Elevated blood creatine phosphokinase	Very often (80–99%)

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 KCNA1 and how often each is seen. Find out more at hpo.jax.org.

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