Aim: Mutations in the promoter and coding region of the bilirubin UDP-glucuronosyltransferase gene (UGT 1A1) are known to be associated with Gilber´s syndrome (GS), although the molecular epidemiology and basis for this syndrome in children has yet to be clarified. Authors aimed at evaluating the frequency ofUGT 1A1t28 polymorphisms in the promotor region of the UDP-glucuronosyltransferase gene (the TATA-box mutation), and their clinical implications in GS. Methods: Analyses of the TATA-box mutations were performed in 53 patients with GS and 27 controls using PCR amplification. Results: Genotypes were assigned as follows: TA(6)/TA(6) (homozygous for a normal allele bearing the sequence [TA](6)TAA), TA(7)/TA(7) (homozygous for an mutated allele with the sequence [TA](7)/TAA), and TA(6)/TA(7) (heterozygous with one on cach allele). Male patients (79.2%) tended to baye GS more frequently than female patients (20.8%). There were significant differences in mean serum bilirubin levels between GS patients and controls (p < 0.0001). Of the 53 GS patients, 94.3% had homozygous TA(7)/TA(7) genotype, and 5.7 % had TA(6)/TA(7). Of 27 controls, the frequency of the abnormal allele was 51.9 %‚ one patient (3.8%) had TA(7)/TA(7), 13 had TA(6)/TA(7) (48.1%), and 13 (48.1%) had normal genotype TA(6)/TA(6). Calculated frequency of TA(7)/TA(7) genotype is 8% in the pediatric population. Conclusion: TATA-box mutations have a significant effect on serum bilirubin levels. I{omozygous TA(7)/TA(7)-box variant of the promoter region of UGT 1A1*28 gene is strongly associated with GS predominantly in male Czech pediatric patients. These results have clear implications for clinical practicc in children with disordcrs of bilirubin mctabolism

        Key words: Gilbcrt‘s syndrome, UGT 1A1t28 polymorphisms, hyperbilirubinemia, TATA-box mutations