The Silent Echoes of Heredity: A Rare Case Report of Crigler–Najjar Syndrome Type II in Syria

Crigler–Najjar Syndrome type II (CNS II) is a rare autosomal recessive disorder caused by mutations that reduce the activity of the uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) enzyme. Since this enzyme is responsible for conjugating (breaking down) bilirubin in the liver, its reduced function leads to elevated levels of unconjugated bilirubin in the blood. A 17-year-old boy with generalized tonic–clonic seizures and cognitive decline had a history of recurrent jaundice from infancy, initially treated with phototherapy and phenobarbital without a definitive diagnosis. Examination and laboratory results showed high unconjugated bilirubin levels, and given the family history, clinical presentation, and phenobarbital response, diagnosis of CNS II was strongly suspected despite the absence of genetic testing. Phenobarbital and plasma exchange significantly reduced bilirubin levels, and lifelong phenobarbital therapy was initiated for clinical stabilization. He underwent liver transplantation in Egypt but died a week later due to immune rejection. This case highlights the importance of innovative diagnostic approaches in resource-limited settings that offer crucial insights into CNS II care.