Genetic testing for Gilbert's syndrome

Abstract

I read with interest the report in your journal by Dr Erdil and colleagues on the use of rifampicin in the diagnosis of Gilbert's syndrome.1 The problem of the lack of specificity of provocative tests for the diagnosis of Gilbert's syndrome can be overcome by molecular genetic testing. Gilbert's syndrome is most frequently due to a mutation in the promoter region of the gene for uridine diphosphate glucoronosyltransferase (UGT1A1) such that an extra TA is added to the TATA box (UGT1A1 TA7).2 Homozygosity for the UGT1A1 TA7) variant is a common cause of Gilbert's syndrome in European and African populations and is reported to occur in 99% of the Spanish population.3 Mutations in the UGT1A1 gene exons are a frequent cause of Gilbert's syndrome phenotype in the Japanese population.4 A definitive diagnosis of Gilbert's syndrome is now possible by molecular genetic testing for UGT1A1 promoter polymorphism and direct analysis of all exons and their flanking regions of the UGT1A and UGT1D genes.5