Crigler Najjar syndrome type 2

ABSTRACT

Background: Crigler Najjar syndrome (CNS) is an extremely rare disorder of bilirubin metabolism that follows an autosomal recessive pattern of inheritance. CNS is elicited by a lack or deficiency of the enzyme uridine diphosphate glucuronyl transferase (UDGT). Two distinct forms have been described type 1 and type 2. Type 1 CNS is associated with neonatal unconjugated hyperbilirubinemia and kernicterus, which results in very high levels of unconjugated hyperbilirubinemia (up to 50 mg/dL) at birth. Type 2 CNS presents with serum bilirubin levels up to 20 mg/dL and markedly depressed activity of hepatic UDGT are characteristic of type 2 CNS. Objective: To rule out other causes for unconjugated hyperbilirubinemia, and arrive at a definitive diagnosis of Crigler Najjar syndrome type 2. Methods: Clinical examination of the baby and laboratory investigations like hemoglobin, complete blood count, thyroid profile, liver function tests and ultrasound were carried out. Results: Except for unconjugated hyperbilirubinemia, all other reports were within the normal range. Conclusion: Laboratory investigations and the response of the baby to phototherapy and phenobarbitone with decrease in the serum unconjugated bilirubin levels lead to a diagnosis of Crigler Najjar syndrome type 2. Hepatic glucuronyl transferase activity in a liver specimen, obtained by a closed biopsy and in vitro expression of mutant DNA from patient fibroblast, would have been helpful for definitive diagnosis.