Traits

Traits linked to TBCK

TBC1 domain containing kinase

The Human Phenotype Ontology links 143 traits to TBCK, 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
Absent reflexes	Always
Bilateral tonic-clonic seizure with focal onset	Always
Delayed speech and language development	Always
Extra-axial cerebrospinal fluid accumulation	Always
Global developmental delay	Always
Hyperintensity of cerebral white matter on MRI	Always
IQ less than 20	Always
Profound global developmental delay	Always
Reduced brain N-acetyl aspartate level by MRS	Always
Thin corpus callosum	Always
Ventriculomegaly	Always
Decreased reflex response	Very often (80–99%)
Motor delay	Very often (80–99%)
Abnormal periventricular white matter morphology	Often (30–79%)
Absent speech development	Often (30–79%)
Decreased compound muscle action potential amplitude	Often (30–79%)
Diminished deep tendon reflex	Often (30–79%)
Epilepsy	Often (30–79%)
Generalized brain degeneration	Often (30–79%)
Inability to walk	Often (30–79%)
Loss of developmental milestones	Often (30–79%)
Multifocal epileptiform discharges	Often (30–79%)
Multifocal seizures	Often (30–79%)
Severe global developmental delay	Often (30–79%)
Too much cerebrospinal fluid in the brain	Often (30–79%)
Underdevelopment of part of brain called corpus callosum	Often (30–79%)
Cognitive impairment	Sometimes (5–29%)
Degeneration of cerebellum	Sometimes (5–29%)
EEG with generalized epileptiform discharges	Sometimes (5–29%)
Partial agenesis of the corpus callosum	Sometimes (5–29%)
Periventricular leukomalacia	Sometimes (5–29%)
Autism	Rarely (1–4%)
Bipolar disorder	Rarely (1–4%)
Brain degeneration	Not recorded
Cerebellar vermis hypoplasia	Not recorded
Degeneration of cerebrum	Not recorded
Dysplastic corpus callosum	Not recorded
Encephalopathy	Not recorded
Poor speech	Not recorded
Small basal ganglia	Not recorded
Small cerebellum	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Enlarged cisterna magna	Always
Broad head shape	Very often (80–99%)
Exaggerated cupid's bow	Very often (80–99%)
Narrow forehead	Very often (80–99%)
Abnormal facial shape	Often (30–79%)
Abnormally large tongue	Often (30–79%)
Big calvaria	Often (30–79%)
Coarse facial features	Often (30–79%)
Gum enlargement	Often (30–79%)
High palate	Often (30–79%)
Highly arched eyebrow	Often (30–79%)
Nasal tip, upturned	Often (30–79%)
Prominent nasal bridge	Often (30–79%)
Tented mouth	Often (30–79%)
Big lower jaw	Sometimes (5–29%)
Broad forehead	Sometimes (5–29%)
Bulbous nose	Sometimes (5–29%)
Eye folds	Sometimes (5–29%)
Full lips	Sometimes (5–29%)
High, narrow palate	Sometimes (5–29%)
Little lower jaw	Sometimes (5–29%)
Long eyelashes	Sometimes (5–29%)
Long philtrum	Sometimes (5–29%)
Monobrow	Sometimes (5–29%)
Myopathic facies	Sometimes (5–29%)
Open mouth	Sometimes (5–29%)
Prominent metopic ridge	Sometimes (5–29%)
Short neck	Sometimes (5–29%)
Sloping forehead	Sometimes (5–29%)
Tall shaped head	Sometimes (5–29%)
Thick eyebrow	Sometimes (5–29%)
Upward slanting of the opening between the eyelids	Sometimes (5–29%)
Wide nasal bridge	Sometimes (5–29%)
Abnormally small head	Rarely (1–4%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Axial muscle weakness	Always
Delayed bone maturation	Always
Distal muscle wasting	Always
Funnel chest	Always
Generalized decreased muscle tone	Always
Increased variability in muscle fiber diameter	Always
Low muscle tone	Always
Severely decreased muscle tone	Always
EMG: chronic denervation signs	Very often (80–99%)
Low muscle tone, in neonatal onset	Very often (80–99%)
Progressive muscle weakness	Very often (80–99%)
EMG: myokymic discharges	Often (30–79%)
Joint contracture	Often (30–79%)
Muscle degeneration	Often (30–79%)
Osteoporosis	Often (30–79%)
11 pairs of ribs	Sometimes (5–29%)
Scoliosis	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Bulging eye	Always
Cerebral visual impairment	Often (30–79%)
Cross-eyed	Often (30–79%)
Involuntary, rapid, rhythmic eye movements	Often (30–79%)
Wide-set eyes	Often (30–79%)
Clouding of the lens of the eye	Sometimes (5–29%)
Corneal opacity	Sometimes (5–29%)
Deeply set eye	Sometimes (5–29%)
Drooping upper eyelid	Sometimes (5–29%)
Inward turning cross eyed	Sometimes (5–29%)
Abnormal involuntary eye movements	Rarely (1–4%)

Abnormality of limbs

Trait	How often it is seen
Acromelia	Always
Limb muscle weakness	Always
Overlapping toe	Always
Single transverse palmar crease	Always
Limb undergrowth	Often (30–79%)
Tapered finger	Often (30–79%)
Broad finger	Sometimes (5–29%)
Broad toe	Sometimes (5–29%)
Curvature of digit	Rarely (1–4%)
Webbed 2nd and 3rd toes	Rarely (1–4%)

Laboratory abnormality

Trait	How often it is seen
Mildly elevated creatine kinase	Always
Abnormal circulating lipid concentration	Often (30–79%)
Elevated serum cholesterol	Often (30–79%)
Increased plasma triglycerides	Often (30–79%)
Intermittent hypothermia	Often (30–79%)
Hypothermia	Sometimes (5–29%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Fetal pyelectasis	Sometimes (5–29%)
High levels of amniotic fluid	Sometimes (5–29%)
Less than 10 fetal movements in 12 hours	Sometimes (5–29%)
Low levels of amniotic fluid	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Always
Gastrostomy tube feeding in infancy	Always
Tube feeding	Often (30–79%)
Gap between large left and right abdominal muscles	Rarely (1–4%)

Abnormality of the endocrine system

Trait	How often it is seen
Underactive thyroid	Often (30–79%)
Central adrenal insufficiency	Rarely (1–4%)
Decreased response to growth hormone stimulation test	Rarely (1–4%)
Overactive thyroid	Rarely (1–4%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Hole in heart wall separating two lower heart chambers	Sometimes (5–29%)
Right aortic arch	Sometimes (5–29%)
Narrowing of pulmonic valve	Rarely (1–4%)

Abnormality of the ear

Trait	How often it is seen
Low-set ears	Sometimes (5–29%)
Hearing impairment	Rarely (1–4%)
Sensorineural hearing impairment	Rarely (1–4%)

Abnormality of the genitourinary system

Trait	How often it is seen
Undescended testes	Often (30–79%)
Lack of bladder control due to nervous system injury	Rarely (1–4%)

Abnormality of the immune system

Trait	How often it is seen
Asthma	Rarely (1–4%)
Eczema	Rarely (1–4%)

Abnormality of the integument

Trait	How often it is seen
Excessive hairiness	Sometimes (5–29%)

Abnormality of the respiratory system

Trait	How often it is seen
Respiratory function loss	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 TBCK and how often each is seen. Find out more at hpo.jax.org.

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