A new frame-shifting mutation of UGT1A1 gene causes type I Crigler-Najjar syndrome.

We present a case of severe persisting unconjugated hyperbilirubinemia in a Uigur infant boy, eventually diagnosed as Crigler-Najjar syndrome type I. DNA analysis of his blood of the UGT1A1 gene sequence demonstrated that he was homozygous for an insertion mutation causing a change of the coding exons with a frame-shift, resulting in the substitution of 27 abnormal amino acid residues in his hepatic bilirubin uridine diphosphoglucuronyl transferase enzyme. Both of his parents were heterozygous for the same mutation. A novel frame-shifting mutation of the UGT1A1 gene was found, confirming the diagnosis of Crigler-Najjar syndrome type I for this patient.