UGT1A1(TA)n promoter polymorphism—A new case of a (TA)8 allele in Caucasians

Gilbert's syndrome is a mild hereditary unconjugated hyperbilirubinemia caused by mutations in the bilirubin UDP-glucuronosyltransferase gene (UGT1A1). The causative mutation in Caucasians is almost exclusively a TA dinucleotide insertion in the TATA box of the UGT1A1 promoter. Affected individuals are homozygous for the variant promoter and have 7 instead of 6 TA repeats. The aim of the present study was to determine the genotypes of UGT1A1(TA)n promoter polymorphism in the healthy Slovenian population and to investigate the association of genotypes with serum bilirubin levels. 236 healthy subjects were genotyped by single-strand conformation polymorphism analysis, which was validated by sequence analysis. The frequencies of genotypes were as follows: (TA)6/6 (38.1%), (TA)6/7 (47.9%), (TA)7/7 (13.6%). There was a statistically significant association of genotypes with serum bilirubin levels (p