Traits

Traits linked to TPP1

tripeptidyl peptidase 1

The Human Phenotype Ontology links 41 traits to TPP1, 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
Ataxia	Always
Degeneration of cerebellum	Always
Explosive speech	Always
Lack of coordination of movement	Always
Truncal titubation	Always
Unsteady walk	Always
Postural tremor	Very often (80–99%)
Progressive cerebellar ataxia	Very often (80–99%)
Abnormal gait	Often (30–79%)
Babinski sign	Often (30–79%)
Clumsiness	Often (30–79%)
Difficulty articulating speech	Often (30–79%)
Impaired vibratory sensation	Often (30–79%)
Increased reflexes	Often (30–79%)
Limb ataxia	Often (30–79%)
Progressive gait ataxia	Often (30–79%)
Wide based walk	Often (30–79%)
Inability to coordinate movements when walking	Sometimes (5–29%)
Abnormal nervous system electrophysiology	Not recorded
Degeneration of cerebrum	Not recorded
Delayed speech and language development	Not recorded
Epilepsy	Not recorded
Increased extraneuronal autofluorescent lipopigment	Not recorded
Increased neuronal autofluorescent lipopigment	Not recorded
Jerking	Not recorded
Loss of developmental milestones	Not recorded

Abnormality of the eye

Trait	How often it is seen
Involuntary, rapid, rhythmic eye movements	Always
Oculomotor apraxia	Always
Double vision	Often (30–79%)
Horizontal nystagmus	Often (30–79%)
Saccadic smooth pursuit interruptions	Often (30–79%)
Uncoordinated eye movement	Often (30–79%)
Hypermetric saccades	Sometimes (5–29%)
Progressive loss of vision	Not recorded
Retina degeneration	Not recorded
Undetectable electroretinogram	Not recorded

Abnormal cellular phenotype

Trait	How often it is seen
Curvilinear intracellular accumulation of autofluorescent lipopigment storage material	Not recorded

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 musculoskeletal system

Trait	How often it is seen
EMG: neuropathic changes	Sometimes (5–29%)

Laboratory abnormality

Trait	How often it is seen
Reduced tissue tripeptidyl peptidase 1 activity	Always

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 TPP1 and how often each is seen. Find out more at hpo.jax.org.

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