Traits

Traits linked to TDO2

tryptophan 2,3-dioxygenase

The Human Phenotype Ontology links 19 traits to TDO2, 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
Aggressive behavior	Not recorded
Amplification of sexual behavior	Not recorded
Can't control feelings	Not recorded
Depression	Not recorded
IQ between 34 and 49	Not recorded
Stuttering	Not recorded

Abnormality of limbs

Trait	How often it is seen
Dropped arches	Not recorded
Inward turned thumb	Not recorded
Limited elbow extension	Not recorded
Permanent flexion of the finger	Not recorded

Abnormality of the eye

Trait	How often it is seen
Close sighted	Not recorded
Cross-eyed	Not recorded
Visual impairment	Not recorded
Wide-set eyes	Not recorded

Laboratory abnormality

Trait	How often it is seen
High blood tryptophan concentration	Always
High urine tryptophan levels	Very often (80–99%)

Abnormality of the ear

Trait	How often it is seen
Sensorineural hearing impairment	Not recorded

Abnormality of the endocrine system

Trait	How often it is seen
Increased serum serotonin	Always

Abnormality of the musculoskeletal system

Trait	How often it is seen
Hypermobility of all joints	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 TDO2 and how often each is seen. Find out more at hpo.jax.org.

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