UGT1A1-28 Genotyping


UDP-glucuronosyltransferase-1A1 or UGT1A1 is an enzyme encoded by the UGT1A1 gene. UGT1A1 is involved in metabolism of several drugs. The promoter of the UGT1A1 gene contains a common variant in the region of the TATA box promoter element. The most common variant A(TA-6)TAA accounts for ~50% of alleles whereas the UGT1A1*28 variant which has an extra TA dinucleotide A(TA-7)TAA can account for up to 40% of alleles. UGT1A1*28 is associated with lower expression levels of UGT1A1. Individuals who are homozygous for the UGT1A1*28 allele (~15% of the population) show reduced levels of glucoronidation by UGT1A1 and are at raised risk of a mild syndrome of hyperbilirubinaemia under conditions of stress (Gilbert syndrome). There is evidence that UGT1A1*28 homozygotes are at raised risk of adverse reactions to drugs that are metabolised by this pathway including irinotecan. UGT1A1*28 status can be used to guide dosage for irinotecan to minimise adverse reaction.

Referral information

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Price & reporting times

Test Price (£ ex VAT) TRT *
UGT1A1*28 genotyping POA 14 calendar days

Test validation & quality assurance - information for users

The test has been internally validated by analysis of a range of control samples with the full range of expected genotypes obtained from an external laboratory carrying out UGT1A1 testing for Gilbert analysis. Samples are genotyped alongside validated control samples representing the 6/6, 6/7 and 7/7 genotypes.

Referral guidelines

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OMIM Number(s) - 191740

Gene(s) - UGT1A1