A novel deletion mutation (c.749 del C) in the UGT1A1 gene as a cause of Crigler-Najjar syndrome type 1: A case report

Abstract

Crigler-Najjar syndrome type I (CNS-1) is a rare inherited disorder, which can lead to kernicterus. Mutations within the UGT1A1 gene that cause the absence of functional UGT1A1 protein/enzyme are the leading cause of CNS-1. UGT1A1 converts unconjugated bilirubin to conjugated form, making it able to be water-soluble and excreted. CNS-1 has a poor prognosis, and timely diagnosis of the disease is necessary to the prevention of kernicterus and successful management of the disease. We identified a novel single nucleotide deletion mutation (c.749 del C) within the first exon of the UGT1A1 gene in a 9-month-old male infant. The patient had total serum bilirubin concentration peaked at 26.8 mg/dL on the 9th day of birth and didn't respond to phototherapy and Phenobarbital and await for the curative liver transplantation. The identified frameshift mutation disrupted the reading frame result in the formation of a premature stop codon. Accordingly, the c.749 del C mutation is a pathogenic mutation that leads to CNS-1.