Persistent unconjugated hyperbilirubinemia after liver transplantation due to an abnormal bilirubin UDP-glucuronosyltransferase gene promotor sequence in the donor

Background/Aims: Gilbertʹs syndrome is genetically characterized by an extra TA element in the TATAA-box of the promotor region upstream of the bilirubin UDP-glucuronosyltransferase (UGT1A) coding region (Bosma et al. N Engl J Med 1995; 333: 1171–1175). Persistent unconjugated hyperbilirubinemia is occasionally observed in liver transplant recipients with an otherwise normal liver function. We postulate that these patients could have received a liver from a donor with the Gilbertʹs syndrome genotype. Therefore, we investigated the UG1A-gene TATAA-box in DNA from liver graft donors of jaundiced and non-jaundiced recipients. Methods: DNA was obtained from stored donor lymphocytes and the number of TA elements in the TATAA-box of the UGT1A-gene promotor region was analyzed by polymerase chain-reaction. Results: We observed two liver transplant recipients with persistent unconjugated hyperbilirubinemia. They received liver grafts from donors who were homozygous for an abnormal A(TA)7TAA-box in the UGT1A-gene. Four of 10 non-jaundiced recipients received livers from donors who were homozygous for the normal A(TA)6TAA-box and six received livers from donors who were heterozygous with a normal A(TA)6TAA-box on one allele and a prolonged A(TA)7 TAA-box on the other allele. Conclusions: This study shows that liver graft recipients with persistent unconjugated hyperbilirubinemia may have received a liver from a donor with an abnormal TATAA-box in the bilirubin UGT1A-gene promotor region.