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encephalopathy due to hydroxykynureninuria - Clinical Profile, Genes & Research | Kisho | Kisho

Rare Disease

encephalopathy due to hydroxykynureninuria

MONDO:0009372

Also known as:Xanthurenic aciduriakynureninase deficiencyhydroxykynureninuria

Overview

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.

GeneticsAutosomal recessive · KYNU (chr 2)

OnsetNEONATAL

ResearchLimited published research (2 articles)

Clinical Presentation

Built from Human Phenotype Ontology (HPO) phenotype annotations and GeneReviews clinical descriptions. Features represent findings documented across known cases — not an exhaustive list of possible symptoms.

Features include always present findings: Elevated urinary xanthurenic acid level, Vomiting, Elevated urinary 3-hydroxykynurenine level, and Jaundice.

Organ System	Phenotype Count	Example Features
Kidneys and urinary system	2	Elevated urinary xanthurenic acid level, Elevated urinary 3-hydroxykynurenine level

Genetic Landscape

Assembled from HGNC gene records, ClinGen gene-disease validity evidence, and ClinVar pathogenic variant data. Validity classifications reflect the strength of published evidence linking each gene to this disease.

KYNU encodes kynureninase (465 aa). Catalyzes the cleavage of L-kynurenine (L-Kyn) and L-3-hydroxykynurenine (L-3OHKyn) into anthranilic acid (AA) and 3-hydroxyanthranilic acid (3-OHAA), respectively. Highest expression in Cells EBV-transformed lymphocytes (6.9 TPM) and Liver (3.7 TPM).

Encephalopathy due to hydroxykynureninuria is associated with mutations in the KYNU gene on chromosome 2.

The KYNU protein participates in 10xdHF-10xglutamyl semialdehyde (Pro)-6xL-tyrosine residue-3xOxoH-2xmodified L-lysine residue-N'-formyl-L-kynurenine-APOB(28-4563), GPR35:Kynurenic acid, and Unknown NAT N-acetylates kynurenine pathways.

KYNU is classified as a druggable target (Druggable Genome and Enzyme categories) with score 0.0.

Diagnosis

Genetic testing for KYNU is available. Testing is considered confirmatory for diagnosis.

Prognosis

Phenotype severity distribution: 4 always present features.

Estimated prevalence: <1 in 1,000,000 (VERY_RARE).

Research Landscape

Sourced from ClinicalTrials.gov and PubMed. Publication types are classified using NLM-curated article metadata; research type breakdowns reflect the nature of published work for this disease.

No clinical trials have been registered for encephalopathy due to hydroxykynureninuria.

2 publications have been identified in PubMed for encephalopathy due to hydroxykynureninuria. Research spans Basic Science / Preclinical (100%).

Recent Publications

Yoshidomi K (2026). [PMID: 41794052](https://pubmed.ncbi.nlm.nih.gov/41794052/). *Neurochem Int*. [Basic Science / Preclinical]
Liu TT (2026). [PMID: 41765652](https://pubmed.ncbi.nlm.nih.gov/41765652/). *Zhonghua Fu Chan Ke Za Zhi*. [Basic Science / Preclinical]

Data assembled from 6 of 12 sources · Last updated Sep 20, 2026, 4:03 PM UTC

MONDOHPOClinicalTrials.govFDAPubMedHGNCClinVarClinGenGeneReviewsOrphanetOMIMRUSP

Medical References

External Resources

OMIM

Online Mendelian Inheritance in Man

OMIM:236800

Orphanet

European rare disease database

Orphanet:79155

GARD

Genetic and Rare Diseases Info Center

GARD:10039

Questions for Your Care Team

→Should my partner and I meet with a genetic counselor to discuss carrier status and family planning?
→Are there specialists or centers of excellence for this condition in my area?
→Is there a patient registry I should consider joining?

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encephalopathy due to hydroxykynureninuria

Overview

Clinical Presentation

Genetic Landscape

Diagnosis

Prognosis

Research Landscape

Recent Publications

Medical References

External Resources

OMIM

Orphanet

GARD

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