Traits

Traits linked to SCN5A

sodium voltage-gated channel alpha subunit 5

The Human Phenotype Ontology links 88 traits to SCN5A, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of the cardiovascular system

Trait	How often it is seen
Prolonged QTc interval	Always
Torsade de pointes	Always
Tricuspid regurgitation	Always
Ventricular flutter	Always
Ventricular tachycardia	Always
Abnormal P wave	Very often (80–99%)
Atrial standstill	Very often (80–99%)
Cardiac conduction abnormality	Very often (80–99%)
Left ventricular systolic dysfunction	Very often (80–99%)
Palpitations	Very often (80–99%)
Reduced left ventricular ejection fraction	Very often (80–99%)
Slow heartbeats	Very often (80–99%)
Stretched and thinned heart muscle	Very often (80–99%)
Ventricular escape rhythm	Very often (80–99%)
Abnormal heart rate	Often (30–79%)
Abnormality of the heart	Often (30–79%)
Bundle branch block	Often (30–79%)
Cardiac failure	Often (30–79%)
Complete right bundle branch block	Often (30–79%)
Fainting spell	Often (30–79%)
Heart block	Often (30–79%)
Heart stops beating	Often (30–79%)
Increased circulating troponin T concentration	Often (30–79%)
Left atrial enlargement	Often (30–79%)
Left ventricular noncompaction	Often (30–79%)
Paroxysmal atrial fibrillation	Often (30–79%)
Permanent atrial fibrillation	Often (30–79%)
Prolonged PR interval	Often (30–79%)
Quivering upper heart chambers resulting in irregular heartbeat	Often (30–79%)
Right ventricular dilatation	Often (30–79%)
Sick sinus syndrome	Often (30–79%)
ST segment elevation	Often (30–79%)
Stroke	Often (30–79%)
Sudden cardiac death	Often (30–79%)
Ventricular fibrillation	Often (30–79%)
Atrial flutter	Sometimes (5–29%)
Disease of the heart muscle	Sometimes (5–29%)
Elevated heart rate	Sometimes (5–29%)
First degree atrioventricular block	Sometimes (5–29%)
Heart attack	Sometimes (5–29%)
Ischemic stroke	Sometimes (5–29%)
Left anterior fascicular block	Sometimes (5–29%)
Left posterior fascicular block	Sometimes (5–29%)
Left ventricular hypertrophy	Sometimes (5–29%)
Mobitz I atrioventricular block	Sometimes (5–29%)
Paroxysmal ventricular tachycardia	Sometimes (5–29%)
Supraventricular tachycardia	Sometimes (5–29%)
Supraventricular tachycardia with an accessory connection mediated pathway	Sometimes (5–29%)
Extra heart beat	Rarely (1–4%)
Left bundle branch block	Rarely (1–4%)
Trifascicular block	Rarely (1–4%)
Ventricular arrhythmia	Rarely (1–4%)
Absent P wave	Not recorded
Complete heart block with broad QRS complexes	Not recorded
Interruption of electrical communication between upper and lower chambers of heart	Not recorded
Premature atrial contractions	Not recorded
Prolonged QT interval	Not recorded
Reduced systolic function	Not recorded
Sinus bradycardia	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Muscular dystrophy	Often (30–79%)
EMG abnormality	Sometimes (5–29%)
Flexed joint that cannot be straightened	Sometimes (5–29%)
Loss of fat tissue in localized area	Sometimes (5–29%)
Muscle degeneration	Sometimes (5–29%)
Muscle tissue disease	Sometimes (5–29%)

Constitutional symptom

Trait	How often it is seen
Chest pain	Often (30–79%)
Decreased ability to exercise	Often (30–79%)
Fatigue	Often (30–79%)
Postexertional symptom exacerbation	Often (30–79%)
Sudden death	Not recorded

Abnormality of the nervous system

Trait	How often it is seen
Difficulty articulating speech	Sometimes (5–29%)
Difficulty finding words	Sometimes (5–29%)
Headache	Sometimes (5–29%)
Paralysis on one side of body	Sometimes (5–29%)

Abnormality of the respiratory system

Trait	How often it is seen
Breathing difficulty	Often (30–79%)
Exertional breathlessness	Often (30–79%)
Orthopnea	Often (30–79%)
Apneic episodes in infancy	Not recorded

Laboratory abnormality

Trait	How often it is seen
Hydrops fetalis	Always
Nonimmune hydrops fetalis	Always
Fluid retention	Often (30–79%)
Malignant hyperthermia	Not recorded

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Thromboembolic stroke	Sometimes (5–29%)
Thromboembolism	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Abdominal pain	Often (30–79%)
Nausea	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Dizziness	Often (30–79%)
Sensorineural hearing impairment	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 SCN5A and how often each is seen. Find out more at hpo.jax.org.

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