encephalopathy due to hydroxykynureninuria
Findings
No curated finding names encephalopathy due to hydroxykynureninuria yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Encephalopathy due to hydroxykynureninuria is characterized by psychomotor retardation and nonprogressive encephalopathy associated with urinary excretion of large amounts of kynurenine, 3-hydroxykynurenine, and xanthurenic acid. It has been described in less than 30 patients. Other manifestations may include muscular hypertonia, headaches and stereotyped gestures. This disorder is transmitted as an autosomal recessive trait. It is caused by a defect in kynureninase, an enzyme of the tryptophane catabolic pathway.
Definition from the Mondo Disease Ontology (MONDO:0009372), read 2026-09-29. CC BY 4.0.
- Inheritance
- Autosomal recessive inheritance
- Onset and course
- Neonatal onset
HPO, annotations 2026-09-02
Features
20 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Abnormal circulating tryptophan concentrationHPOHP:0004365
- Obligate (100% of cases)
- Elevated urinary 3-hydroxykynurenine levelHPOHP:6000265
- 1 of 1 reported patient
- Elevated urinary xanthurenic acid levelHPOHP:6000121
- 1 of 1 reported patient
- EncephalopathyHPOHP:0001298
- Obligate (100% of cases)
- JaundiceHPOHP:0000952
- 1 of 1 reported patient
- VomitingHPO
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- KYNUHGNC:6469
- Strong · Labcorp Genetics (formerly Invitae) · Autosomal recessive · 2018
- Strong · PanelApp Australia · Autosomal recessive · 2025
- Supportive · Orphanet · Autosomal recessive · 2021
- Limited · Ambry Genetics · Autosomal recessive · 2020
Where it sits
Other names
2 names
Resolves to: encephalopathy due to hydroxykynureninuria
- Also called
- kynureninase deficiencyXanthurenic aciduria