Traits

Traits linked to TOE1

target of EGR1, exonuclease

The Human Phenotype Ontology links 64 traits to TOE1, 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
Hypoplasia of the pons	Always
Intellectual disability	Always
Small brainstem	Always
Increased reflexes	Very often (80–99%)
Abnormal cerebral morphology	Often (30–79%)
Abnormal cerebral white matter morphology	Often (30–79%)
Ataxia	Often (30–79%)
Autism spectrum disorder	Often (30–79%)
Choreoathetosis	Often (30–79%)
Jerking	Often (30–79%)
Muscle twitch	Often (30–79%)
Olivopontocerebellar hypoplasia	Often (30–79%)
Underdevelopment of part of brain called corpus callosum	Often (30–79%)
Ventriculomegaly	Often (30–79%)
Epilepsy	Sometimes (5–29%)
Involuntary movements	Sometimes (5–29%)
Too much cerebrospinal fluid in the brain	Sometimes (5–29%)
Absent speech development	Not recorded
Degeneration of cerebrum	Not recorded
Small cerebellum	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Progressively abnormally small cranium	Very often (80–99%)
Abnormally small head	Often (30–79%)
Eye folds	Often (30–79%)
Full upper lip	Often (30–79%)
High palate	Often (30–79%)
Little lower jaw	Often (30–79%)
Wide nasal bridge	Often (30–79%)
Broad nasal tip	Sometimes (5–29%)
Deep philtrum	Sometimes (5–29%)
Depressed nasal bridge	Sometimes (5–29%)
Large forehead	Sometimes (5–29%)
Monobrow	Sometimes (5–29%)
Prominent brow	Sometimes (5–29%)
Tongue twitching	Sometimes (5–29%)
Upward slanting of the opening between the eyelids	Sometimes (5–29%)

Abnormality of the genitourinary system

Trait	How often it is seen
Ambiguous external genitalia	Very often (80–99%)
Undescended testes	Very often (80–99%)
Short penis	Often (30–79%)
Abnormal scrotal rugation	Sometimes (5–29%)
Absent penis	Sometimes (5–29%)
Absent uterus	Sometimes (5–29%)
Enlarged clitoris	Sometimes (5–29%)
Gonadal dysgenesis	Sometimes (5–29%)
Microphallus	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Muscle degeneration	Always
Muscle weakness	Always
Spasticity and rigidity of muscles	Very often (80–99%)
Fatigable weakness of skeletal muscles	Often (30–79%)
Involuntary muscle stiffness, contraction, or spasm	Often (30–79%)
Low muscle tone	Often (30–79%)
Opisthotonus	Sometimes (5–29%)
Pigeon chest	Sometimes (5–29%)
Spastic paraplegia	Not recorded

Abnormality of the eye

Trait	How often it is seen
Involuntary, rapid, rhythmic eye movements	Often (30–79%)
Oculomotor apraxia	Often (30–79%)
Optic atrophy	Often (30–79%)

Abnormality of the ear

Trait	How often it is seen
Large ears	Often (30–79%)
Low-set ears	Sometimes (5–29%)

Abnormality of the integument

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

Abnormality of limbs

Trait	How often it is seen
Single transverse palmar crease	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Always

Abnormality of the respiratory system

Trait	How often it is seen
Apnea	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 TOE1 and how often each is seen. Find out more at hpo.jax.org.

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