Traits

Traits linked to SCN4A

sodium voltage-gated channel alpha subunit 4

The Human Phenotype Ontology links 183 traits to SCN4A, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of the musculoskeletal system

Trait	How often it is seen
Axial muscle weakness	Always
Centrally nucleated skeletal muscle fibers	Always
Difficulty walking up stairs	Always
Diffuse skeletal muscle wasting	Always
EMG: decremental response of compound muscle action potential to repetitive nerve stimulation	Always
EMG: myotonic discharges	Always
Episodic flaccid weakness	Always
Fatigable weakness	Always
Generalized muscle weakness	Always
Handgrip myotonia	Always
Increased skeletal muscle cells	Always
Increased variability in muscle fiber diameter	Always
Low muscle tone	Always
Lower limb pain	Always
Muscle spasm	Always
Muscle stiffness	Always
Muscle tissue disease	Always
Myotonia	Always
Osteoporosis	Always
Percussion myotonia	Always
Prominent swayback	Always
Tired easily	Always
Abnormal muscle fiber morphology	Very often (80–99%)
EMG abnormality	Very often (80–99%)
Low muscle tone, in neonatal onset	Very often (80–99%)
Spasticity and rigidity of muscles	Very often (80–99%)
Cold paresis	Often (30–79%)
Cold-sensitive myotonia	Often (30–79%)
Exercise-induced muscle fatigue	Often (30–79%)
Exercise-induced muscle stiffness	Often (30–79%)
Funnel chest	Often (30–79%)
Gowers sign	Often (30–79%)
Limb contractures	Often (30–79%)
Muscle degeneration	Often (30–79%)
Muscle weakness	Often (30–79%)
Myotonia of the face	Often (30–79%)
Myotonia of the jaw	Often (30–79%)
Myotonia of the lower limb	Often (30–79%)
Myotonia of the upper limb	Often (30–79%)
Paradoxical myotonia	Often (30–79%)
Poorly developed skeletal musculature	Often (30–79%)
Scoliosis	Often (30–79%)
Decreased lung function due to weak breathing muscles	Sometimes (5–29%)
EMG: myopathic abnormalities	Sometimes (5–29%)
Fatty replacement of skeletal muscle	Sometimes (5–29%)
Flexed joint that cannot be straightened	Sometimes (5–29%)
Frequent falls	Sometimes (5–29%)
Generalized decreased muscle tone	Sometimes (5–29%)
Generalized increase in muscle cell size	Sometimes (5–29%)
Hunched back	Sometimes (5–29%)
Late-onset proximal muscle weakness	Sometimes (5–29%)
Limitation of joint mobility	Sometimes (5–29%)
Reduced spine movement	Sometimes (5–29%)
Shoulder flexion contracture	Sometimes (5–29%)
Slender long bone	Sometimes (5–29%)
Small chest	Sometimes (5–29%)
Thin ribs	Sometimes (5–29%)
Thoracic scoliosis	Sometimes (5–29%)
Fatigable weakness of respiratory muscles	Rarely (1–4%)
Myotonia with warm-up phenomenon	Rarely (1–4%)
Proximal neurogenic muscle weakness	Rarely (1–4%)
Respiratory paralysis	Rarely (1–4%)

Abnormality of head or neck

Trait	How often it is seen
Downward slanting of the opening between the eyelids	Always
High forehead	Always
High palate	Always
Open mouth	Always
Scaphocephaly	Always
Short neck	Always
Weakness of facial musculature	Very often (80–99%)
Frontal bossing	Often (30–79%)
Increased size of facial muscles	Often (30–79%)
Increased stiffness of facial muscles	Often (30–79%)
Little lower jaw	Often (30–79%)
Long face	Often (30–79%)
Dental crowding	Sometimes (5–29%)
Eye folds	Sometimes (5–29%)
Monobrow	Sometimes (5–29%)
Receding chin	Sometimes (5–29%)
Short nose	Sometimes (5–29%)
Short philtrum	Sometimes (5–29%)
Tented mouth	Sometimes (5–29%)
Triangular mouth	Sometimes (5–29%)
Wide nasal bridge	Sometimes (5–29%)

Abnormality of the nervous system

Trait	How often it is seen
Abnormal gait	Always
Absent reflexes	Always
Motor delay	Always
Normal pressure hydrocephalus	Always
Paralysis	Always
Periodic hypokalemic paresis	Always
Periodic paralysis	Always
Cerebral palsy	Very often (80–99%)
Diminished deep tendon reflex	Very often (80–99%)
Periodic hyperkalemic paralysis	Very often (80–99%)
Communication delay	Often (30–79%)
Muscle twitch	Often (30–79%)
Waddling gait	Often (30–79%)
Intellectual disability	Sometimes (5–29%)
Leukoencephalopathy	Sometimes (5–29%)
Pins and needles feeling	Sometimes (5–29%)
Choking episodes	Rarely (1–4%)

Abnormality of limbs

Trait	How often it is seen
Club foot on both sides	Always
Curvature of digit	Always
Dislocated hip since birth	Always
High-arched foot	Always
Hyporeflexia of lower limbs	Always
Limb muscle weakness	Always
Proximal lower limb muscle weakness	Always
Hip contracture	Often (30–79%)
Talipes	Often (30–79%)
Congenital finger flexion contractures	Sometimes (5–29%)
Elbow flexion contracture	Sometimes (5–29%)
Knee contracture	Sometimes (5–29%)
Pes valgus	Sometimes (5–29%)
Shortening of the achilles tendon	Sometimes (5–29%)
Tapered toe	Sometimes (5–29%)
Winged shoulder blade	Sometimes (5–29%)

Laboratory abnormality

Trait	How often it is seen
Low blood potassium levels	Always
Mildly elevated creatine kinase	Always
Recurrent low potassium	Always
Elevated blood creatine phosphokinase	Very often (80–99%)
Increased intramyocellular lipid droplets	Very often (80–99%)
Increased circulating potassium concentration	Often (30–79%)
Nonimmune hydrops fetalis	Often (30–79%)
Postprandial hyperglycemia	Often (30–79%)
Abnormal circulating potassium concentration	Sometimes (5–29%)
Fluid around lungs	Sometimes (5–29%)
Low blood sodium levels	Sometimes (5–29%)
Malignant hyperthermia	Sometimes (5–29%)
Hyperkalemia while symptomatic	Not recorded

Abnormality of the eye

Trait	How often it is seen
Cross-eyed	Always
Drooping of both upper eyelids	Always
Drooping upper eyelid	Always
Esodeviation	Always
Involuntary, rapid, rhythmic eye movements	Always
Paralysis or weakness of muscles within or surrounding outer part of eye	Always
Eye muscle paralysis	Often (30–79%)
Blurred vision	Sometimes (5–29%)
Bulging eye	Sometimes (5–29%)
Deeply set eye	Sometimes (5–29%)
Double vision	Sometimes (5–29%)
Weakness of muscles controlling eye movement	Sometimes (5–29%)

Abnormality of the respiratory system

Trait	How often it is seen
Apnea	Always
Breathing difficulty	Always
Noisy breathing	Always
Respiratory function loss	Always
Neonatal inspiratory stridor	Often (30–79%)
Poorly developed lungs	Often (30–79%)
Breathing difficulties	Sometimes (5–29%)
Laryngospasm	Rarely (1–4%)
Apneic episodes in infancy	Not recorded
Inspiratory stridor	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Often (30–79%)
Poor swallowing	Often (30–79%)
Accumulation of fluid in the abdomen	Sometimes (5–29%)
Enlarged liver	Sometimes (5–29%)
Feeding difficulties in infancy	Sometimes (5–29%)
Loss of bowel control	Sometimes (5–29%)
Tube feeding	Sometimes (5–29%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Slow heartbeats	Always
Abnormal heart rate	Sometimes (5–29%)
Cardiac failure	Sometimes (5–29%)
Tricuspid regurgitation	Sometimes (5–29%)
Impaired myocardial contractility	Not recorded

Constitutional symptom

Trait	How often it is seen
Chest tightness	Always
Fatigue	Always
Muscle ache	Always
Chest pain	Often (30–79%)
Pain	Sometimes (5–29%)

Abnormality of prenatal development or birth

Trait	How often it is seen
High levels of amniotic fluid	Always
Feet or buttocks of fetus positioned near opening of uterus	Often (30–79%)
Less than 10 fetal movements in 12 hours	Often (30–79%)

Abnormality of the voice

Trait	How often it is seen
Nasal speech	Always
Weak cry	Often (30–79%)
Abnormality of the voice	Sometimes (5–29%)

Abnormality of the endocrine system

Trait	How often it is seen
Underactive thyroid	Sometimes (5–29%)
Adrenocortical adenoma	Rarely (1–4%)

Abnormality of the immune system

Trait	How often it is seen
Anti-neuromuscular Junction acetylcholine receptor antibody positivity	Often (30–79%)
Asthma	Sometimes (5–29%)

Abnormal cellular phenotype

Trait	How often it is seen
Decreased activity of mitochondrial complex I	Always

Abnormality of the breast

Trait	How often it is seen
Enlarged male breast	Always

Abnormality of the ear

Trait	How often it is seen
Low-set ears	Sometimes (5–29%)

Abnormality of the integument

Trait	How often it is seen
Blue discoloration of the skin	Always

Growth abnormality

Trait	How often it is seen
Short stature	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 SCN4A and how often each is seen. Find out more at hpo.jax.org.

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