Traits

Traits linked to TBC1D2B

TBC1 domain family member 2B

The Human Phenotype Ontology links 18 traits to TBC1D2B, 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
Epilepsy	Always
EEG with occipital epileptiform discharges	Often (30–79%)
Inability to coordinate movements when walking	Often (30–79%)
Inappropriate laughter	Often (30–79%)
Intellectual disability, mild	Often (30–79%)
Loss of developmental milestones	Often (30–79%)
Slurred speech	Often (30–79%)
Degeneration of cerebellum	Sometimes (5–29%)
EEG with generalized epileptiform discharges	Sometimes (5–29%)
Inappropriate crying	Sometimes (5–29%)
Ventriculomegaly	Sometimes (5–29%)

Abnormality of head or neck

Trait	How often it is seen
Coarse facial features	Often (30–79%)
Gum enlargement	Often (30–79%)
Jaw swelling	Often (30–79%)

Abnormality of limbs

Trait	How often it is seen
Flexion contracture of toe	Often (30–79%)
Permanent flexion of the finger	Often (30–79%)

Abnormality of the eye

Trait	How often it is seen
Optic atrophy	Often (30–79%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Low muscle tone in trunk	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 TBC1D2B and how often each is seen. Find out more at hpo.jax.org.

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