Gilbert's syndrome and hyperbilirubinaemia in ABO-incompatible neonates

We asked whether UDP glucuronosyltransferase (UGT) gene promoter polymorphi sm (Gilbert's syndrome) would increase hyperhilirubinaemia in direct Coombs ' negative ABO-Incompatible neonates, as seen in other combinations with th is condition. 40 ABO-incompatible and 344 ABO-compatible controls had an al lele frequency of 0.35 for the variant promoter gene. The incidence of hype rbilirubinaemia was significantly higher only In the former who were also h omozygotes for the variant UGT promoter, compared with ABO-incompatible bab ies homozygous for the normal UGT promoter (43% vs 0, p=0.02), and with ABO -compatible controls of all UGT genotypes combined (relative risk 5.65, 95% CI 2.23-14.31). Gilbert's syndrome is a determining factor for neonatal hy perbilirubinaemia ABO incompatibility.