Skip to content

IEMbase 0661: UGT1A1-related UDP-glucuronosyltransferase A1 deficiency

Scope

Field Value
IEMbase ID 661
Nosology 17.2.01.01
Nosology code IEM0802
Gene UGT1A1
External IDs OMIM:218800; OMIM:606785; ORPHA:205
Generated mapping MAPPED to Gilberts_Syndrome.yaml
Candidate DisMech targets Gilberts_Syndrome.yaml covers mild Gilbert physiology only
Review date 2026-07-07

IEMbase phenotype signal

IEMbase represents autosomal recessive UGT1A1-related UDP-glucuronosyltransferase A1 deficiency with both severe Crigler-Najjar syndrome and milder Gilbert syndrome named as alternate labels.

Clinical rows include persistent jaundice across all ages, neonatal temperature instability, abnormal eye movements, convulsions, and hearing loss. The convulsion row increases from optional neonatal involvement to strong childhood/adolescent involvement, consistent with bilirubin neurotoxicity scope. The biochemical row includes increased plasma bilirubin.

DisMech phenotype coverage

Gilberts_Syndrome.yaml is a correct target for the mild Gilbert end of the UGT1A1 spectrum. It models reduced UGT1A1 activity, impaired bilirubin glucuronidation, mild unconjugated hyperbilirubinemia, intermittent jaundice, UGT1A128 and UGT1A16 genetics, and pharmacogenomic irinotecan relevance. It also references Crigler-Najjar type II versus Gilbert bilirubin concentrations in supporting evidence.

However, the local entry is explicitly a benign Gilbert syndrome entry. It does not model Crigler-Najjar syndrome as a disease entity, profound neonatal unconjugated hyperbilirubinemia, bilirubin encephalopathy/kernicterus, abnormal eye movements, seizures/convulsions, hearing loss, temperature instability, or Crigler-Najjar-specific treatment intensity such as phototherapy or liver transplantation.

Concordance and completeness

Judgement: partial mapping only. Accept Gilberts_Syndrome.yaml for the mild Gilbert component, but do not treat it as complete coverage for the IEMbase UGT1A1 deficiency spectrum.

The generated high-confidence alias match is understandable because IEMbase lists Gilbert syndrome, but the same row also names severe Crigler-Najjar syndrome. A single Gilbert entry under-covers the severe bilirubin-neurotoxicity phenotype package.

Curation actions

  • Keep Gilberts_Syndrome.yaml as the mild-spectrum target.
  • Add or map a separate Crigler-Najjar syndrome target if DisMech wants full UGT1A1 deficiency spectrum coverage.
  • Preserve bilirubin, neonatal temperature instability, abnormal eye movements, convulsions/seizures, hearing loss, and persistent jaundice prompts.
  • Avoid claiming full row-level completeness from the Gilbert mapping alone.