Molecular Analysis of the UGT1A1 Gene in Korean Patients with Crigler-Najjar Syndrome Type II

Purpose: Crigler-Najjar syndrome type II (CN-2) is characterized by moderate non-hemolytic unconjugated hyperbilirubinemia as a result of severe deficiency of bilirubin uridine diphosphate-glucuronosyltransferase (UGT1A1). The study investigated the mutation spectrum of UGT1A1 gene in Korean children with CN-2. Methods: Five Korean CN-2 patients from five unrelated families and 50 healthy controls were enrolled. All five exons and flanking introns of the UGT1A1 gene were amplified by polymerase chain reaction (PCR) and the PCR products were directly sequenced. Results: All children initially presented with neonatal jaundice and had persistent indirect hyperbilirubinemia. Homozygous p. Y486D was identified in all five patients. Three patients had an associated homozygous p. G71R and two a heterozygous p. G71R. The allele frequency of p. Y486D and p. G71R in healthy controls was 0 and 0.16, respectively. No significant difference in mean serum bilirubin levels was found between homozygous carriers of p. G71R and heterozygous carriers. Conclusion: The combination of homozygous p. Y486D and homozygous or heterozygous p. G71R is identified. The p. Y486D and p. G71R can be screened for the mutation analysis of UGT1A1 in Korean CN-2 patients.