Traits

Traits linked to OTC

ornithine transcarbamylase

The Human Phenotype Ontology links 45 traits to OTC, by body system: features seen in people with one of the gene's rare conditions.

Laboratory abnormality

Trait	How often it is seen
High blood ammonia levels	Always
Abnormal urinary amino-acid findings	Very often (80–99%)
Elevated circulating uracil concentration	Very often (80–99%)
High urine orotic acid levels	Very often (80–99%)
Low blood sugar	Very often (80–99%)
Decreased circulating citrulline concentration	Often (30–79%)
Elevated circulating alanine aminotransferase concentration	Often (30–79%)
Elevated circulating aspartate aminotransferase concentration	Often (30–79%)
High liver enzymes	Often (30–79%)
Hypothermia	Often (30–79%)
Low blood arginine levels	Often (30–79%)
Respiratory alkalosis	Often (30–79%)
Conjugated hyperbilirubinemia	Sometimes (5–29%)
High plasma glutamine	Sometimes (5–29%)
Brain swelling	Not recorded
Episodic ammonia intoxication	Not recorded
Reduced hepatic ornithine transcarbamylase activity	Not recorded

Abnormality of the nervous system

Trait	How often it is seen
Coma	Often (30–79%)
Drowsiness	Often (30–79%)
Encephalopathy	Often (30–79%)
Epilepsy	Often (30–79%)
Lethargy	Often (30–79%)
Anxiety	Sometimes (5–29%)
Attention deficit	Sometimes (5–29%)
Delirium	Sometimes (5–29%)
Depression	Sometimes (5–29%)
Global developmental delay	Sometimes (5–29%)
Irritability	Sometimes (5–29%)
Specific learning disability	Sometimes (5–29%)
Ataxia	Not recorded
Episodic ataxia	Not recorded
Intellectual disability	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Liver failure	Very often (80–99%)
Anorexia	Often (30–79%)
Poor suck	Often (30–79%)
Protein avoidance	Often (30–79%)
Vomiting	Often (30–79%)
Abdominal pain	Sometimes (5–29%)
Episodic vomiting	Sometimes (5–29%)

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Prolonged partial thromboplastin time	Sometimes (5–29%)
Prolonged prothrombin time	Sometimes (5–29%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Increased spleen size	Very often (80–99%)
Stroke	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Low muscle tone	Often (30–79%)

Growth abnormality

Trait	How often it is seen
Faltering weight	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 OTC and how often each is seen. Find out more at hpo.jax.org.

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