Crigler-Najjar syndrome type 2
Findings
No curated finding names Crigler-Najjar syndrome type 2 yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Type 2 Crigler-Najjar syndrome (CNS2) is a hereditary disorder of bilirubin metabolism characterized by unconjugated hyperbilirubinemia due to reduced and inducible activity of hepatic bilirubin glucuronosyltransferase (GT). CNS2 is a milder form of CNS than CNS1.
Definition from the Mondo Disease Ontology (MONDO:0011725), read 2026-09-29. CC BY 4.0.
- Inheritance
- Autosomal recessive inheritance
HPO, annotations 2026-09-02
Features
6 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.
- JaundiceHPOHP:0000952
- 7 of 7 reported patients
- Unconjugated hyperbilirubinemiaHPOHP:0008282
- 8 of 8 reported patients
- Very frequent (80% to 99% of cases)
- Neonatal hyperbilirubinemiaHPOHP:0003265
- Very frequent (80% to 99% of cases)
- Prolonged neonatal jaundiceHPOHP:0006579
- Very frequent (80% to 99% of cases)
- Elevated circulating hepatic transaminase concentrationHPOHP:0002910
- 0 of 7 reported patients
- Reduced tissue UDP-glucuronyl-transferase activityHPOHP:6000617
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.
- UGT1A1HGNC:12530
- Definitive · Ambry Genetics · Autosomal recessive · 2018
- Strong · PanelApp Australia · Autosomal recessive · 2025
- Supportive · Orphanet · Autosomal recessive · 2021
Where it sits
- A kind of
Other names
5 names
Resolves to: Crigler-Najjar syndrome type 2
- Also called
- Arias syndromebilirubin uridinediphosphate glucuronosyltransferase deficiency type 2bilirubin-UGT deficiency type 2hereditary unconjugated hyperbilirubinemia type 2UGT deficiency type 2