Crigler-Najjar Type 1 Syndrome: Absence of Hepatic Bilirubin UDP-Glucuronyl Transferase Activity and Therapeutic Response to Light

Abstract

A 16-yr-old boy with severe congenital unconjugated hyperbilirubinemia is described in whom mental retardation occurred as an isolated neurological deficit. The diagnosis of Crigler-Najjar type 1 syndrome was supported by an extreme and persistent elevation of serum unconjugated bilirubin (650 .mu.mol/l), failure of administered phenobarbitone to lower serum bilirubin concentration and family history of a similarly affected sibling. Hepatic bilirubin UDP-glucuronyl transferase activity, determined in vitro by a sensitive new enzyme assay, was absent when using bilirubin or bilirubin monoglucuronide as substrate. Phototherapy for 12 h each night produced a partial, but highly significant reduction in serum bilirubin concentration, which was not influenced further by the administration of cholestyramine.