OBJECTIVETo analyze potential mutations of uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) gene in patients with unconjugated hyperbilirubinemia, and to explore the correlation between the mutations and total serum bilirubin levels.

METHODSGenomic DNA was extracted from peripheral blood samples of patients. Coding sequence and promoter region of the UGT1A1 gene were amplified. Mutations were identified through DNA sequencing.

RESULTSMutations of the UGT1A1 gene were found in 46 out of 61 patients with unconjugated hyperbilirubinemia. Five types of mutations were detected, with a decreasing order of 211G>A, TA insertion in the TATAA promoter element, 686C>A, 1091C>T and 1352C>T. Compared with those carrying a single homozygous mutation or compound heterozygous mutations, total serum bilirubin was higher in those carrying a homozygous mutation in combination with other heterozygous mutations (P< 0.05). Based on the UGT1A1 gene mutations and level of total serum bilirubin, 44 patients were diagnosed with Gilbert syndrome, and 2 were diagnosed with Crigler-Najjar syndrome type 2.

CONCLUSIONThe level of total serum bilirubin is correlated with the number of UGT1A1 gene mutations as well as their heterozygous or homozygous status.