Crigler–Najjar (type 1 and 2) syndrome:
- Is due to deficiency of enzyme uridine diphosphate glucuronyltransferase(ugt).
- Autosomal recessive disorder.
- Both types present in the early neonatal period with a rapid rise in serum bilirubin to very high levels despite phototherapy.
- Kernicterus can develop.
- Type 1 is more severe.
Gilbert syndrome
- Autosomal recessive condition in which UGT1A1 activity decreases mildly in hepatocytes, typically resulting in a benign unconjugated hyperbilirubinemia.
- The likelihood of severe hyperbilirubinemia is increased if the infant also has G6PD deficiency.