Traits

Traits linked to TBC1D23

TBC1 domain family member 23

The Human Phenotype Ontology links 38 traits to TBC1D23, 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
Global developmental delay	Always
Happy demeanor	Always
Hypoplasia of the pons	Always
Intellectual disability, severe	Always
Repetitive movements	Always
Small cerebellum	Always
Autism spectrum disorder	Often (30–79%)
Underdevelopment of part of brain called corpus callosum	Often (30–79%)
Agenesis of corpus callosum	Sometimes (5–29%)
Attention deficit	Sometimes (5–29%)
Self-injurious behavior	Sometimes (5–29%)
Abnormal gait	Not recorded
Ataxia	Not recorded
Decreased reflex response	Not recorded
Delayed speech and language development	Not recorded
Difficulty articulating speech	Not recorded
Inability to walk	Not recorded
Incoordination	Not recorded
Limb ataxia	Not recorded
Poor eye contact	Not recorded
Wide based walk	Not recorded

Abnormality of the eye

Trait	How often it is seen
Cross-eyed	Often (30–79%)
Notched pupil	Often (30–79%)
Farsightedness	Sometimes (5–29%)
Inward turning cross eyed	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Involuntary muscle stiffness, contraction, or spasm	Always
Generalized decreased muscle tone	Not recorded
Muscle degeneration	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Bulbous nose	Often (30–79%)
Abnormally small head	Not recorded

Abnormality of limbs

Trait	How often it is seen
Club feet	Sometimes (5–29%)
Dropped arches	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Absent anus	Sometimes (5–29%)
Poor swallowing	Not recorded

Growth abnormality

Trait	How often it is seen
Decreased body weight	Not recorded
Short stature	Not recorded

Abnormality of the ear

Trait	How often it is seen
Large ears	Always

Abnormality of the immune system

Trait	How often it is seen
Recurrent respiratory infections	Not recorded

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 TBC1D23 and how often each is seen. Find out more at hpo.jax.org.

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