Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

UGT2
89611
(before phototherapy becomes ineffective). The UGT1A1 gene maps to chromosome 2q37 and contains 5
exons. Currently, there are more than 130 known mutations in UGT1A1, with 45 mutations that cause a
decrease in UGT1A1 enzyme activity. Analysis is performed for the familial mutation only.
Useful For: Identifying the presence of a UGT1A1 mutation when the mutation has been identified
in a family member (carrier or affected)
Interpretation: An interpretive report will be provided.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Guilemette C: Pharmacogenomics of human UDP-glucuronosyltransferase
enzymes. Pharmacogenomics J 2003;3:136-158 2. Innocenti F, Grimsley C, Das S, et al: Haplotype
structure of the UDP-glucuronosyltransferase 1A1 promoter in different ethnic groups.
Pharmacogenetics 2002;12:725-733 3. Costa E, Vieira E, Martins M, et al: Analysis of the
UDP-glucuronosyltransferase gene in Portuguese patients with a clinical diagnosis of Gilbert and
Crigler-Najjar syndromes. Blood Cells Mol Dis 2006;36:91-97 4. Kitagawa C, Ando M, Ando Y, et al:
Genetic polymorphism in the Phenobarbital- responsive enhancer module of the
UDP-glucuronosyltransferase 1A1 gene and irinotecan toxicity. Pharmacogenet Genomics
2005;15:35-41
UDP-Glucuronosyl Transferase 1A1 (UGT1A1), Full Gene
Sequencing, Hyperbilirubinemia
Clinical Information: Bilirubin, resulting from the breakdown of heme, is a water-insoluble toxic
compound. Uridine diphosphate (UDP)-glycuronosyl transferase 1A1 (UGT1A1) is responsible for
bilirubin conjugation with glucuronic acid. This renders the bilirubin water soluble and permits
excretion of the bilirubin-glucuronide conjugates in urine.(1) Genetic mutations in the UGT1A1 gene
may cause reduced or absent UGT1A1 enzymatic activity resulting in hyperbilirubinemia (eg, Gilbert
syndrome, Crigler-Najjar). Gilbert syndrome, found in 5% to 10% of the population, is the most
common hereditary cause of increased bilirubin and is associated with mild hyperbilirubinemia
(bilirubin levels are typically around 3 mg/dL).(2) Gilbert syndrome is caused by a 25% to 50% reduced
glucuronidation activity of the UGT1A1 enzyme and characterized by episodes of mild intermittent
jaundice and the absence of liver disease. Crigler-Najjar (CN) types I and II are inherited causes of
severe unconjugated hyperbilirubinemia. CN type I is associated with no UGT1A1 enzymatic activity
and usually presents as intense jaundice in the first days of life and persists thereafter.(3) Type II is a
milder form in which bilirubin levels are