Traits

Traits linked to GRIA4

glutamate ionotropic receptor AMPA type subunit 4

The Human Phenotype Ontology links 30 traits to GRIA4, 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
Intellectual disability	Always
Absent speech development	Often (30–79%)
Delayed ability to walk	Often (30–79%)
Epilepsy	Often (30–79%)
Exaggerated startle response	Often (30–79%)
Irritability	Often (30–79%)
Short attention span	Often (30–79%)
Chorea	Sometimes (5–29%)
Decrease in size of the outer layer of the brain due to loss of brain cells	Sometimes (5–29%)
EEG with generalized slow activity	Sometimes (5–29%)
Inability to walk	Sometimes (5–29%)
Repeated seizures without recovery between them	Sometimes (5–29%)
Underdevelopment of part of brain called corpus callosum	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Involuntary muscle stiffness, contraction, or spasm	Often (30–79%)
Spasticity and rigidity of muscles	Often (30–79%)
Joint contracture	Sometimes (5–29%)
Low muscle tone, in neonatal onset	Sometimes (5–29%)
Spastic tetraplegia	Sometimes (5–29%)

Abnormality of head or neck

Trait	How often it is seen
Abnormally small head	Sometimes (5–29%)
Big lower jaw	Sometimes (5–29%)
Midface retrusion	Sometimes (5–29%)
Short philtrum	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Cross-eyed	Sometimes (5–29%)
Involuntary, rapid, rhythmic eye movements	Sometimes (5–29%)
Optic nerve hypoplasia	Sometimes (5–29%)

Growth abnormality

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

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Sometimes (5–29%)

Abnormality of the ear

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

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 GRIA4 and how often each is seen. Find out more at hpo.jax.org.

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