Mondo Description Crigler-Najjar syndrome (CNS) is a hereditary disorder of bilirubin metabolism characterized by unconjugated hyperbilirubinemia due to a hepatic deficit of bilirubin glucuronosyltransferase (GT) activity. Two types have been described, CNS types 1 and 2. CNS1 is characterized by a complete deficit of the enzyme and is unaffected by phenobarbital induction therapy, whereas the enzymatic deficit is partial and responds to phenobarbital in CNS2.

Disease Ontology Description A bilirubin metabolic disorder that involves a build up of bilirubin as bilirubin is not being broken down as a result of a lack or deficiency of the enzyme uridine diphosphate glycosyltransferase (UGT).