Traits

Traits linked to AMPD2

adenosine monophosphate deaminase 2

The Human Phenotype Ontology links 43 traits to AMPD2, 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
Abnormal gait	Always
Abnormal periventricular white matter morphology	Always
Babinski sign	Always
Delayed ability to walk	Always
Delayed social development	Always
Global developmental delay	Always
Hypoplasia of the pons	Always
Increased reflexes	Always
Intellectual disability	Always
Irritability	Always
Small cerebellum	Always
Underdevelopment of part of brain called corpus callosum	Always
Absent speech development	Often (30–79%)
Clonus	Often (30–79%)
Delayed motor skills	Often (30–79%)
Dystonia	Often (30–79%)
Epilepsy	Often (30–79%)
Impaired vibration sensation at ankles	Often (30–79%)
Ventriculomegaly	Often (30–79%)
Periventricular leukomalacia	Sometimes (5–29%)
Decrease in size of the outer layer of the brain due to loss of brain cells	Not recorded
Peripheral axonal neuropathy	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Development of small head that was not present at birth	Always
Abnormally large tongue	Not recorded
Decreased facial muscle tone	Not recorded
Downward slanting of the opening between the eyelids	Not recorded
Midface retrusion	Not recorded
Narrow forehead	Not recorded
Short upper lip	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Involuntary muscle stiffness, contraction, or spasm	Always
Scissor gait	Always
Spasticity and rigidity of muscles	Always
Muscle degeneration	Often (30–79%)
Low muscle tone in trunk	Sometimes (5–29%)
Spastic paraplegia	Not recorded

Abnormality of the eye

Trait	How often it is seen
Visual fixation instability	Very often (80–99%)
Cerebral visual impairment	Often (30–79%)
Optic atrophy	Often (30–79%)
Cross-eyed	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Decreased body weight	Often (30–79%)
Short stature	Often (30–79%)

Abnormality of the digestive system

Trait	How often it is seen
Poor swallowing	Very often (80–99%)

Abnormality of the ear

Trait	How often it is seen
Abnormally shaped ears	Not recorded

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 AMPD2 and how often each is seen. Find out more at hpo.jax.org.

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