<prompt> Which of the following is true about Criggler Najar type 1?Less severe than type 2Phenobarbitone improves bilirubin by 25Bile is colourlessPhototherapy is main stay of treatment  <response>: Impaired bilirubin conjugation occurs in three genetic conditions: Crigler-Najjar syndrome types I and II and Gilbes syndrome. Crigler-Najjar type I is an exceptionally rare condition found in neonates and characterized by severe jaundice bilirubin 342 mmolL and neurologic impairment due to kernicterus, frequently leading to death in infancy or childhood.These patients have a complete absence of bilirubin UDPGT activity and are totally unable to conjugate bilirubin, and hence cannot excrete it.Crigler-Najjar type II is somewhat more common than type I. Patients live into adulthood with serum bilirubin levels of 103-428 mmolL 6-25 mgdL.In these patients, mutations in the bilirubin UDPGT gene cause the reduction--but not the complete eradication--of the enzymes activity. Bilirubin UDPGT activity can be induced by the administration of phenobarbital, which can reduce serum bilirubin levels in these patients.Ref: Harrison; 19th edition; Page no: 282 