Traits

Traits linked to TRIO

trio Rho guanine nucleotide exchange factor

The Human Phenotype Ontology links 106 traits to TRIO, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of head or neck

Trait	How often it is seen
Abnormal dentition	Often (30–79%)
Abnormally small head	Often (30–79%)
Big calvaria	Often (30–79%)
Dental crowding	Often (30–79%)
Facial asymmetry	Often (30–79%)
Frontal bossing	Often (30–79%)
Full lips	Often (30–79%)
Fullness around the eyes	Often (30–79%)
High forehead	Often (30–79%)
Little lower jaw	Often (30–79%)
Monobrow	Often (30–79%)
Small head present at birth	Often (30–79%)
Bulbous nose	Sometimes (5–29%)
Depressed nasal bridge	Sometimes (5–29%)
Development of small head that was not present at birth	Sometimes (5–29%)
Downward slanting of the opening between the eyelids	Sometimes (5–29%)
Eye folds	Sometimes (5–29%)
Failure of development of more than six teeth	Sometimes (5–29%)
Failure of eruption of tooth	Sometimes (5–29%)
High palate	Sometimes (5–29%)
Highly arched eyebrow	Sometimes (5–29%)
Long philtrum	Sometimes (5–29%)
Low frontal hairline	Sometimes (5–29%)
Low hanging columella	Sometimes (5–29%)
Midface retrusion	Sometimes (5–29%)
Nasal tip, upturned	Sometimes (5–29%)
Prominent nasal bridge	Sometimes (5–29%)
Receding chin	Sometimes (5–29%)
Short chin	Sometimes (5–29%)
Short nose	Sometimes (5–29%)
Short philtrum	Sometimes (5–29%)
Slanting of the opening between the eyelids	Sometimes (5–29%)
Thick eyebrow	Sometimes (5–29%)
Thin red part of the upper lip	Sometimes (5–29%)
Underdeveloped tissue around nostril	Sometimes (5–29%)
Upward slanting of the opening between the eyelids	Sometimes (5–29%)
Wide mouth	Sometimes (5–29%)
Wide nasal bridge	Sometimes (5–29%)

Abnormality of the nervous system

Trait	How often it is seen
Delayed ability to walk	Always
Delayed speech and language development	Always
Intellectual disability	Always
Motor delay	Always
Global developmental delay	Very often (80–99%)
Intellectual disability, mild	Very often (80–99%)
Poor speech	Very often (80–99%)
Aggressive behavior	Often (30–79%)
Attention deficit	Often (30–79%)
Autism spectrum disorder	Often (30–79%)
Behavioral abnormality	Often (30–79%)
Epilepsy	Often (30–79%)
Increased reflexes	Often (30–79%)
Obsessive-compulsive trait	Often (30–79%)
Repetitive movements	Often (30–79%)
Absent speech development	Sometimes (5–29%)
Delayed ability to sit	Sometimes (5–29%)
Difficulty sleeping	Sometimes (5–29%)
Hyperacusis	Sometimes (5–29%)
Inability to coordinate movements when walking	Sometimes (5–29%)
Intellectual disability, borderline	Sometimes (5–29%)
Obsessive compulsive behavior	Sometimes (5–29%)
Pain insensitivity	Sometimes (5–29%)
Self-injurious behavior	Sometimes (5–29%)
Self-mutilation	Sometimes (5–29%)
Specific learning disability	Sometimes (5–29%)
Tremor	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Tapered finger	Often (30–79%)
Webbed 2nd and 3rd toes	Often (30–79%)
Abnormality of the hand	Sometimes (5–29%)
Absent 1st long bone of hand	Sometimes (5–29%)
Curvature of little finger	Sometimes (5–29%)
Dropped arches	Sometimes (5–29%)
Gap between 1st and 2nd toes	Sometimes (5–29%)
Partial absence of thumb	Sometimes (5–29%)
Short fingers or toes	Sometimes (5–29%)
Short palm	Sometimes (5–29%)
Single transverse palmar crease	Sometimes (5–29%)
Unilateral radial aplasia	Sometimes (5–29%)
Winged shoulder blade	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Chronic constipation	Often (30–79%)
Feeding difficulties	Often (30–79%)
Feeding difficulties in infancy	Often (30–79%)
Poor swallowing	Often (30–79%)
Gastrostomy tube feeding in infancy	Sometimes (5–29%)
Poor suck	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Congenital drooping upper eyelid	Sometimes (5–29%)
Cross-eyed	Sometimes (5–29%)
Drooping upper eyelid	Sometimes (5–29%)
Lazy eye	Sometimes (5–29%)
Wide-set eyes	Sometimes (5–29%)

Abnormality of the cardiovascular system

Trait	How often it is seen
An opening in the wall separating the top two chambers of the heart	Sometimes (5–29%)
Complete atrioventricular canal defect	Sometimes (5–29%)
Hole in heart wall separating two lower heart chambers	Sometimes (5–29%)
Patent ductus arteriosus	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Hunched back	Often (30–79%)
Scoliosis	Often (30–79%)
Funnel chest	Sometimes (5–29%)
Low muscle tone	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Large ears	Sometimes (5–29%)
Overfolded ears	Sometimes (5–29%)

Abnormality of the integument

Trait	How often it is seen
Excessive hairiness	Sometimes (5–29%)
Frontal upsweep of hair	Sometimes (5–29%)

Abnormality of the genitourinary system

Trait	How often it is seen
Loss of bladder control	Sometimes (5–29%)

Abnormality of the immune system

Trait	How often it is seen
Recurrent infections	Always

Constitutional symptom

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

Growth abnormality

Trait	How often it is seen
Faltering weight	Sometimes (5–29%)

Laboratory abnormality

Trait	How often it is seen
High blood calcium levels	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 TRIO and how often each is seen. Find out more at hpo.jax.org.

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