Crigler-Najjar syndrome type 2

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Crigler-Najjar syndrome type 2

ORPHA:79235Clinical subtype

Also called Bilirubin uridinediphosphate glucuronosyltransferase deficiency type 2 · Bilirubin-UGT deficiency type 2

What it is

A form of Crigler Najjar syndrome (CNS), a rare hereditary disorder of bilirubin metabolism, characterized by unconjugated hyperbilirubinemia due to reduced and inducible activity of hepatic UDP-glucuronosyltransferase 1A1. The disorder clinically manifests with neonatal, isolated jaundice with a risk of developing bilirubin encephalopathy later in life due to triggers such as stress or infection.

Key facts

Age of onset
Infancy, Neonatal
Inheritance
Autosomal recessive
Classified as
Clinical subtype

Recorded for the broader condition

Prevalence
1-9 / 100 000 (Europe)Crigler-Najjar syndrome

Orphanet records these for the broader condition rather than for this specific form. They are a starting point, not a figure for this subtype — subtypes often differ, and some are defined by being rarer than the condition they sit under.

Signs and symptoms

These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.

Gene

UGT1A1Disease-causing germline mutation(s) (loss of function)

ICD-10 codes

E80.5filed under a broader ICD-10 category — shared with 2 other rare diseases

ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.

Related health topics

Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.

Cross-references

GARD 8683MEDDRA 10011387MESH C536213MONDO 0011725OMIM 606785UMLS C2931132

Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.

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