Rapid UGT1A1 (TA)(n) genotyping by high resolution melting curve analysis for Gilbert's syndrome diagnosis

BACKGROUND: The basis of Gilbert's syndrome is a 70% reduction in bilirubin glucuronidation which, in the Caucasian population, is the result of a homozygous TA insertion into the promoter region of the UDP-glucuronosyltransferase 1A1 (UGT1A1) gene (UGT1A128 allele). In addition, homozygous subjects for UGT1A128 genotype may suffer from severe irinotecan toxicity or jaundice during treatment with the protease inhibitor atazanavir. For these reasons it is very important to perform a correct molecular diagnosis. In this study, we describe for the first time a new high resolution melting (HRM) analysis for a rapid UGT1A1 (TA)(n) genotyping. METHODS: We screened the TA number repetitions of the TATA-box promoter region of the UGT1A1 gene in 30 patients attending the Gemelli Hospital. In order to evaluate the reliability of this technique, we compared the results obtained by HRM and sequencing. RESULTS: Since the TA insertion modifies the derivative melting curve shape and the melting temperature (T(m)), all possible genotypes for the 6 and 7 repeat alleles were successfully identified. CONCLUSIONS: HRM analysis for the UGT1A1 (TA)(n) genotyping is a simple, rapid, sensitive and low cost method, very useful in diagnostics.