Crigler-Najjar syndrome type I (CN-I) is a rare and severe autosomal recessive disorder of bilirubin metabolism. It is characterized by congenital familial nonhemolytic jaundice associated with high level of unconjugated bilirubin resulting from deficiency of uridine diphosphate glucuronosyltransferase (UDPG-T) activity in the liver. The high serum level of unconjugated bilirubin results in kernicterus and neurological sequelae, which can ultimately lead to severe disability or death. Crigler-Najjar syndrome type I can be diagnosed by analysing the clinical presentation, excluding other persistent unconjugated hyperbilirubinemia conditions in infancy, and non-responsiveness to phenobarbitone therapy. The only effective treatment for CN-I patients is orthotopic liver transplantation.
Crigler-Najjar syndrome type I is associated with mutations in UGT1A1 gene.