Traits

Traits linked to TRAPPC12

trafficking protein particle complex subunit 12

The Human Phenotype Ontology links 39 traits to TRAPPC12, 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
Agenesis of corpus callosum	Always
Decrease in size of the outer layer of the brain due to loss of brain cells	Always
Dystonia	Always
Encephalopathy	Always
Extra-axial cerebrospinal fluid accumulation	Always
Hypoplasia of the pons	Always
Jerking	Always
Loss of developmental milestones	Always
Severe global developmental delay	Always
Simplified gyral pattern	Always
Ventriculomegaly	Always
Epilepsy	Often (30–79%)
Epileptic spasm	Often (30–79%)
Hyperintensity of cerebral white matter on MRI	Often (30–79%)
Hypsarrhythmia	Often (30–79%)
Partial agenesis of the corpus callosum	Often (30–79%)
Small cerebellum	Often (30–79%)
Underdeveloped optic tract	Often (30–79%)
Inability to move vocal cords	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Always
Poor swallowing	Always
Acid reflux	Often (30–79%)
Gastrostomy tube feeding in infancy	Often (30–79%)

Abnormality of the eye

Trait	How often it is seen
Cerebral visual impairment	Often (30–79%)
Hypoplastic optic chiasm	Often (30–79%)
Optic atrophy	Often (30–79%)
Increased cup-to-disc ratio	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Appendicular spasticity	Always
Low muscle tone in trunk	Always
Scoliosis	Always
Involuntary muscle stiffness, contraction, or spasm	Often (30–79%)

Abnormality of head or neck

Trait	How often it is seen
Abnormally small head	Always
Small head present at birth	Often (30–79%)
Development of small head that was not present at birth	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Partial hip dislocation	Sometimes (5–29%)

Abnormality of prenatal development or birth

Trait	How often it is seen
High levels of amniotic fluid	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Hearing impairment	Always

Abnormality of the genitourinary system

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

Laboratory abnormality

Trait	How often it is seen
Increased CSF lactate	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 TRAPPC12 and how often each is seen. Find out more at hpo.jax.org.

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