A rare case of Crigler-Najjar syndrome type 2: A case report and literature review.

KEY CLINICAL MESSAGE: Crigler-Najjar syndrome type 2 should be suspected in any young patient presenting with isolated indirect hyperbilirubinemia where all other common etiologies have been excluded. It is a relatively benign condition that responds to phenobarbitone.

ABSTRACT: Crigler-Najjar syndrome (CNS) type 2 is an inborn cause of isolated indirect hyperbilirubinemia characterized by a partial deficiency of the enzyme uridine 5'-diphosphate-glucuronosyltransferase (UGT) responsible for bilirubin conjugation. Typically, this condition is diagnosed based on clinical manifestations, supplemented by enzyme analysis if feasible, and exhibits a significant response to phenobarbitone, known for its enzyme-inducing properties. In this case, we present a young male patient who had experienced recurrent isolated indirect hyperbilirubinemia since early childhood, with negative results in the hemolytic workup. The patient exhibited a UGT1A1 gene defect and demonstrated a highly favorable response to phenobarbitone treatment. The purpose of this report is to raise awareness among physicians about this benign condition and underscore the importance of avoiding unnecessary investigations.