Traits

Traits linked to GABBR2

gamma-aminobutyric acid type B receptor subunit 2

The Human Phenotype Ontology links 112 traits to GABBR2, 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
Absent speech development	Always
Autism spectrum disorder	Always
Developmental stagnation	Always
Epileptic encephalopathy	Always
Inability to walk	Always
Inappropriate crying	Always
Infantile spasms	Always
Intellectual disability	Always
Intellectual disability, severe	Always
Loss of developmental milestones	Always
Recurrent hand flapping	Always
Sleep-wake cycle disturbance	Always
Teeth grinding	Always
Abnormal gait	Very often (80–99%)
Abnormality of movement	Very often (80–99%)
Agitation	Very often (80–99%)
Difficulty sleeping	Very often (80–99%)
EEG abnormality	Very often (80–99%)
Encephalopathy	Very often (80–99%)
Epilepsy	Very often (80–99%)
Involuntary movements	Very often (80–99%)
Loss of speech	Very often (80–99%)
Poor eye contact	Very often (80–99%)
Stereotypical hand wringing	Very often (80–99%)
Abnormality of coordination	Often (30–79%)
Apraxia	Often (30–79%)
Ataxia	Often (30–79%)
Decreased reflex response	Often (30–79%)
Delayed speech and language development	Often (30–79%)
Dystonia	Often (30–79%)
EEG with multifocal slow activity	Often (30–79%)
Focal clonic seizure	Often (30–79%)
Focal impaired awareness seizure	Often (30–79%)
Global developmental delay	Often (30–79%)
Grand mal seizures	Often (30–79%)
Hand apraxia	Often (30–79%)
Hypsarrhythmia	Often (30–79%)
Inability to coordinate movements when walking	Often (30–79%)
Inability to speak	Often (30–79%)
Limb myoclonus	Often (30–79%)
Loss of ability to walk	Often (30–79%)
Multifocal epileptiform discharges	Often (30–79%)
Neonatal seizure	Often (30–79%)
Poor social interactions	Often (30–79%)
Restrictive behavior	Often (30–79%)
Self-injurious behavior	Often (30–79%)
Severe global developmental delay	Often (30–79%)
Tongue thrusting	Often (30–79%)
Tonic seizure	Often (30–79%)
Abnormal corpus callosum morphology	Sometimes (5–29%)
Abnormal myelination	Sometimes (5–29%)
Attention deficit	Sometimes (5–29%)
Autism	Sometimes (5–29%)
Behavioral abnormality	Sometimes (5–29%)
Brain degeneration	Sometimes (5–29%)
Degeneration of cerebrum	Sometimes (5–29%)
Delayed motor skills	Sometimes (5–29%)
Diminished deep tendon reflex	Sometimes (5–29%)
Disorder of involuntary muscle movements	Sometimes (5–29%)
Generalized myoclonic seizure	Sometimes (5–29%)
Impaired pain sensation	Sometimes (5–29%)
Impulsivity	Sometimes (5–29%)
Inappropriate laughter	Sometimes (5–29%)
Intellectual disability, mild	Sometimes (5–29%)
Jerking	Sometimes (5–29%)
Mental deterioration	Sometimes (5–29%)
Panic attack	Sometimes (5–29%)
Pill-rolling tremor	Sometimes (5–29%)
Tremor	Sometimes (5–29%)
Unsteady walk	Sometimes (5–29%)
Repeated seizures without recovery between them	Rarely (1–4%)
Abnormal autonomic nervous system physiology	Not recorded
Ventriculomegaly	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Functional motor deficit	Very often (80–99%)
Abnormal muscle tone	Often (30–79%)
Generalized decreased muscle tone	Often (30–79%)
Involuntary muscle stiffness, contraction, or spasm	Often (30–79%)
Low muscle tone	Often (30–79%)
Poor head control	Often (30–79%)
Hunched back	Sometimes (5–29%)
Low muscle tone, in neonatal onset	Sometimes (5–29%)
Rigidity	Sometimes (5–29%)
Scoliosis	Sometimes (5–29%)

Abnormality of head or neck

Trait	How often it is seen
Development of small head that was not present at birth	Often (30–79%)
Abnormally small head	Sometimes (5–29%)
Downward slanting of the opening between the eyelids	Sometimes (5–29%)
Failure of development of between one and six teeth	Sometimes (5–29%)
High forehead	Sometimes (5–29%)
Big calvaria	Not recorded
Drooling	Not recorded

Abnormality of the eye

Trait	How often it is seen
Drooping upper eyelid	Sometimes (5–29%)
Involuntary, rapid, rhythmic eye movements	Sometimes (5–29%)
Abnormal involuntary eye movements	Rarely (1–4%)
Abnormality of vision	Rarely (1–4%)
Optic atrophy	Rarely (1–4%)
Retina degeneration	Rarely (1–4%)
Total ophthalmoplegia	Not recorded

Abnormality of the respiratory system

Trait	How often it is seen
Rapid breathing	Always
Abnormal pattern of respiration	Very often (80–99%)
Episodic tachypnea	Often (30–79%)
Sudden episodic apnea	Often (30–79%)
Apnea	Not recorded

Abnormality of limbs

Trait	How often it is seen
Short foot	Always
Small hand	Often (30–79%)
Increased muscle tone of arm or leg	Rarely (1–4%)

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Very often (80–99%)
Functional abnormality of the gastrointestinal tract	Often (30–79%)
Acid reflux	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Faltering weight	Often (30–79%)
Growth delay	Sometimes (5–29%)
Short stature	Sometimes (5–29%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Less than 10 fetal movements in 12 hours	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 GABBR2 and how often each is seen. Find out more at hpo.jax.org.

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