Crigler-Najjar Syndrome

Snapshot

• An infant is brought to the pediatrician by his parents because they are concerned about the yellow color of his skin and general behavior changes. They report that he has seemed more tired and weak with his arms just flopping down by his side instead of him reaching for his toys. The parents are known to be first cousins. 

Introduction

• Hereditary unconjugated hyperbilirubinemia 
  • mutation in gene coding for UDP-glucuronosyltransferase (UGT), which normally catalyzes the conjugation of bilirubin and glucuronic acid within hepatocytes 
• Type I
  • absent UGT activity
  • intense jaundice within the first days of life with high risk for kernicterus
  • life-threatening, especially without swift treatment
• Type II
  • markedly reduced level of UGT activity
  • lower serum bilirubin levels, kernicterus is rare
• good prognosis

Presentation

• Symptoms
  • neonatal jaundice
  • sepsis
  • hypotonia
  • kernicterus 
    • deafness
    • poor mental progression/development
• Physical exam
  • jaundice
• oculomotor palsy

Studies

• Labs
  • normal liver function tests 
    • AST, ALT, and alkaline phosphatase
  • unconjugated hyperbilirubinemia
    • type I has high serum bilirubin concentration (20-50 mg/dL)
• type II has lower serum bilirubin concentration (< 20 mg/dL)

Treatment

• Type I
  • phototherapy 
  • plasmapheresis rapidly removes albumin, which is tightly bound to bilirubin 
  • liver transplantation is the only definitive treatment 
• Type II
  • responsive to phenobarbital, which induces residual UGT activity 
    • its usage can differentiate between type I and type II 
    • reduction of serum bilirubin is expected within 2-3 weeks 
• no other treatments are usually indicated 

Complications

• Kernicterus
  • bilirubin deposition in brain
  • poor development/mental function
• If severe, patients die within a few years