Traits

Traits linked to UNC13A

unc-13 homolog A

The Human Phenotype Ontology links 180 traits to UNC13A, 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
Abnormal gait	Always
Absent speech development	Always
Action tremor	Always
Aggressive behavior	Always
Anxiety	Always
Ataxia	Always
Autism	Always
Autism spectrum disorder	Always
Axonal spheroids	Always
Bilateral tonic-clonic seizure with focal onset	Always
Bilateral tonic-clonic seizure with generalized onset	Always
Decreased compound muscle action potential amplitude	Always
Decreased reflex response	Always
Degeneration of the spinal cord	Always
Delayed ability to walk	Always
Delayed speech and language development	Always
Difficulty articulating speech	Always
Disorder of involuntary muscle movements	Always
EEG with burst suppression	Always
EEG with central sharp waves	Always
Epilepsy	Always
Febrile seizure (within the age range of 3 months to 6 years)	Always
Focal impaired awareness seizure	Always
Gliosis	Always
Grand mal seizures	Always
Inability to coordinate movements when walking	Always
Inability to walk by childhood/adolescence	Always
Inappropriate laughter	Always
Instability or lack of coordination of central trunk muscles	Always
Intellectual disability	Always
Intellectual disability, mild	Always
Intellectual disability, severe	Always
Intention tremor	Always
IQ between 34 and 49	Always
Irritability	Always
Limb tremor	Always
Lou Gehrig's disease	Always
More active than typical	Always
Motor delay	Always
Multifocal epileptiform discharges	Always
Multifocal seizures	Always
Pain insensitivity	Always
Poor eye contact	Always
Psychosis	Always
Simple febrile seizure	Always
Speech apraxia	Always
Tonic seizure	Always
Tremor	Always
Weakness of one side of body	Always
Motor neuron atrophy	Very often (80–99%)
Ongoing loss of nerve cells	Very often (80–99%)
Absent reflexes	Often (30–79%)
Babinski sign	Often (30–79%)
Behavioral abnormality	Often (30–79%)
Can't control feelings	Often (30–79%)
Cognitive impairment	Often (30–79%)
Depression	Often (30–79%)
Generalized-onset seizure	Often (30–79%)
Hoffmann sign	Often (30–79%)
Hypsarrhythmia	Often (30–79%)
Increased reflexes	Often (30–79%)
Infantile spasms	Often (30–79%)
IQ less than 20	Often (30–79%)
Muscle twitch	Often (30–79%)
Paralysis	Often (30–79%)
Repeated seizures without recovery between them	Often (30–79%)
Seizure affecting one half of brain	Often (30–79%)
Tetraparesis	Often (30–79%)
Thin corpus callosum	Often (30–79%)
Degeneration of cerebrum	Sometimes (5–29%)
Delayed CNS myelination	Sometimes (5–29%)
Difficulty sleeping	Sometimes (5–29%)
Epileptic encephalopathy	Sometimes (5–29%)
Fluid-filled sac located in membrane surrounding brain or spinal cord	Sometimes (5–29%)
Frontotemporal dementia	Sometimes (5–29%)
High stepping	Sometimes (5–29%)
Jaw hyperreflexia	Sometimes (5–29%)
Language impairment	Sometimes (5–29%)
Periventricular leukomalacia	Sometimes (5–29%)
Reduced cerebral white matter volume	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Congenital diaphragmatic hernia	Always
EMG: decremental response of compound muscle action potential to repetitive nerve stimulation	Always
EMG: myopathic abnormalities	Always
Excessive inward curvature of lower spine	Always
Generalized muscle weakness	Always
Generalized osteoporosis	Always
Kyphoscoliosis	Always
Low muscle tone	Always
Osteopenia	Always
Osteoporosis	Always
Scoliosis	Always
Spastic diplegia	Always
Spastic hemiparesis	Always
Thoracolumbar scoliosis	Always
Type 1 muscle fiber predominance	Always
Type 2 muscle fiber atrophy	Always
Distal muscle wasting	Often (30–79%)
Fatigable weakness of bulbar muscles	Often (30–79%)
Fatigable weakness of respiratory muscles	Often (30–79%)
Fatigable weakness of swallowing muscles	Often (30–79%)
Involuntary muscle stiffness, contraction, or spasm	Often (30–79%)
Muscle degeneration	Often (30–79%)
Muscle spasm	Often (30–79%)
Progressive distal muscular atrophy	Often (30–79%)
Spastic paraparesis	Sometimes (5–29%)
Spasticity and rigidity of muscles	Sometimes (5–29%)

Abnormality of head or neck

Trait	How often it is seen
Broad forehead	Always
Broad philtrum	Always
Decreased size of nasal tip	Always
Depressed nasal bridge	Always
Drooping lower lip	Always
High forehead	Always
High palate	Always
Narrow forehead	Always
Nasal tip, upturned	Always
Short opening between the eyelids	Always
Smooth philtrum	Always
Submucous cleft palate	Always
Underdeveloped tissue around nostril	Always
Wide nasal bridge	Always
Decreased salivary flow	Often (30–79%)
Development of small head that was not present at birth	Often (30–79%)
Drooling	Often (30–79%)
Wasting of the tongue	Often (30–79%)
Tongue twitching	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Curvature of little finger	Always
Dropped arches	Always
Hip dislocation	Always
Increased muscle tone of arm or leg	Always
Knee contracture	Always
Knock knees	Always
Partial hip dislocation	Always
Decreased arm strength	Often (30–79%)
Lower limb muscle weakness	Often (30–79%)
Foot drop	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Acid reflux	Always
Enlarged liver	Always
Episodic vomiting	Always
Feeding difficulties	Always
Inguinal hernia	Always
Intrahepatic inclusion bodies	Always
Poor suck	Always
Poor swallowing	Always
Umbilical hernia	Always

Abnormality of the eye

Trait	How often it is seen
Cerebral visual impairment	Always
Cross-eyed	Always
Deeply set eye	Always
Involuntary, rapid, rhythmic eye movements	Always
Inward turning cross eyed	Always
Outward facing eye ball	Always
Wide-set eyes	Always
Drooping upper eyelid	Often (30–79%)

Abnormality of the respiratory system

Trait	How often it is seen
Cough	Always
Respiratory failure	Always
Stiff lung or chest wall causing decreased lung volume	Always
Ventilator dependence with inability to wean	Always
Abnormality on pulmonary function testing	Often (30–79%)
Breathing difficulty	Often (30–79%)
Orthopnea	Sometimes (5–29%)
Laryngospasm	Rarely (1–4%)

Growth abnormality

Trait	How often it is seen
Faltering weight	Always
Tall stature	Always
Truncal obesity	Always
Short stature	Often (30–79%)
Weight loss	Often (30–79%)
Wasting syndrome	Sometimes (5–29%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Fetal distress	Always
Less than 10 fetal movements in 12 hours	Always
Premature rupture of membranes	Always

Abnormality of the immune system

Trait	How often it is seen
Aspiration pneumonia	Always
Asthma	Always
Recurrent respiratory infections	Always

Abnormality of the ear

Trait	How often it is seen
Hearing abnormality	Always
Sensorineural hearing impairment	Always

Constitutional symptom

Trait	How often it is seen
Fatigue	Often (30–79%)
Pain	Often (30–79%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Patent foramen ovale	Always

Abnormality of the genitourinary system

Trait	How often it is seen
Undescended testes	Always

Abnormality of the integument

Trait	How often it is seen
Excessive hair growth	Always

Abnormality of the voice

Trait	How often it is seen
Inability to produce voice sounds	Often (30–79%)

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 UNC13A and how often each is seen. Find out more at hpo.jax.org.

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