Traits

Traits linked to HPDL

4-hydroxyphenylpyruvate dioxygenase like

The Human Phenotype Ontology links 43 traits to HPDL, 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 cerebral white matter morphology	Always
Intellectual disability	Always
Motor delay	Always
Overactive lower leg reflex	Always
Unsteady walk	Always
Babinski sign	Often (30–79%)
Decreased sensory nerve conduction velocity	Often (30–79%)
Elevated brain lactate level by MRS	Often (30–79%)
Epilepsy	Often (30–79%)
Inability to coordinate movements when walking	Often (30–79%)
Loss of developmental milestones	Often (30–79%)
Underdevelopment of part of brain called corpus callosum	Often (30–79%)
Axial dystonia	Sometimes (5–29%)
Decreased motor nerve conduction velocity	Sometimes (5–29%)
Pins and needles feeling	Sometimes (5–29%)

Abnormality of head or neck

Trait	How often it is seen
Abnormally small head	Often (30–79%)
Drooling	Sometimes (5–29%)
High palate	Sometimes (5–29%)
Long eyelashes	Sometimes (5–29%)
Long philtrum	Sometimes (5–29%)
Nasal tip, upturned	Sometimes (5–29%)
Receding chin	Sometimes (5–29%)
Short neck	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Visual impairment	Often (30–79%)
Esodeviation	Sometimes (5–29%)
Exodeviation	Sometimes (5–29%)
Involuntary, rapid, rhythmic eye movements	Sometimes (5–29%)
Inward turning cross eyed	Sometimes (5–29%)
Paralysis or weakness of muscles within or surrounding outer part of eye	Sometimes (5–29%)
Wide-set eyes	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Spastic paraplegia	Always
Flexed joint that cannot be straightened	Often (30–79%)
Increased variability in muscle fiber diameter	Often (30–79%)
Muscle spasm	Often (30–79%)
Scoliosis	Sometimes (5–29%)

Growth abnormality

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

Laboratory abnormality

Trait	How often it is seen
Higher than normal levels of lactate in blood	Often (30–79%)
Increased CSF lactate	Often (30–79%)

Abnormality of the digestive system

Trait	How often it is seen
Poor swallowing	Sometimes (5–29%)

Abnormality of the genitourinary system

Trait	How often it is seen
Urinary urgency	Sometimes (5–29%)

Abnormality of the respiratory system

Trait	How often it is seen
Respiratory failure requiring assisted ventilation	Often (30–79%)

Constitutional symptom

Trait	How often it is seen
Muscle ache	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 HPDL and how often each is seen. Find out more at hpo.jax.org.

One test. A lifetime of answers.

From $449Free shipping · Results in 6–8 weeks

Get my Genome Test