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Test ID U1A1 UDP-Glucuronosyl Transferase 1A1 TA Repeat Genotype, UGT1A1

Useful For

Identifying individuals who are at increased risk of adverse drug reactions with drugs that are metabolized by UGT1A1; especially irinotecan, but also including nilotinib, pazopanib, and belinostat

 

Identifying individuals with Gilbert syndrome due to the presence of homozygous TA7, homozygous TA8, or compound heterozygous TA7/TA8

 

Identifying individuals who are carriers of Gilbert syndrome due to the presence of heterozygous TA7 or TA8

Genetics Test Information

This genetic test interrogates the thymine-adenine (TA) repeat in the TATA-box of the promoter region of UGT1A1. Repeat number may vary from 5 to 8 TA repeats, with 6 TA repeats representing the most common (normal) number of repeats. Individuals with more than 6 TA repeats may have an increased risk for adverse drug reactions to drugs metabolized by UGT1A1, especially irinotecan, nilotinib, pazopanib, and belinostat. Homozygosity for TA7, TA8, or compound heterozygosity for TA7/TA8 is also consistent with a diagnosis of Gilbert syndrome. Heterozygosity for TA7 or TA8 is consistent with carrier status for Gilbert syndrome.

Method Name

Polymerase Chain Reaction (PCR) with Fragment Analysis by Capillary Gel Electrophoresis

Reporting Name

UGT1A1 TA Repeat Genotype

Specimen Type

Whole Blood EDTA

Specimen Required

Multiple whole blood EDTA genotype tests can be performed on a single specimen after a single extraction. See Multiple Whole Blood EDTA Genotype Tests in Special Instructions for a list of tests that can be ordered together.

 

Container/Tube: Lavender top (EDTA) or lavender top (EDTA) microtube

Specimen Volume: 3 mL

Collection Instructions:

1. Send specimen in original tube.

2. If submitting specimen in microtube, place inside a larger tube or vial for transport.

Specimen Minimum Volume

0.3 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole Blood EDTA Ambient (preferred)
  Refrigerated 

Reference Values

An interpretive report will be provided.

Day(s) and Time(s) Performed

Monday, Wednesday, Friday; Varies

Performing Laboratory

Mayo Medical Laboratories in Rochester

CPT Code Information

81350-UGT1A1 (UDP glucuronosyltransferase 1 family, polypeptide AI) (eg, irinotecan metabolism), gene analysis, common variants (eg, *28, *36, *37)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
U1A1 UGT1A1 TA Repeat Genotype In Process

 

Result ID Test Result Name Result LOINC Value
26615 TA/TA 41044-9
83949 UGT1A1 TA Repeat Genotype In Process
26616 Reviewed by No LOINC Needed

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

Testing Algorithm

See UGT1A1 Test-Ordering Algorithm in Special Instructions.

Forms

1. New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (T576) is available in Special Instructions.

2. If not ordering electronically, complete, print, and send an Oncology Test Request Form (T729) with the specimen

(http://www.mayomedicallaboratories.com/it-mmfiles/oncology-request-form.pdf)

Advisory Information

This test does not detect or report variants other than the *28 (TA7), *36 (TA5), and *37 (TA8) alleles. Numerous variants outside of the TA repeat region have been described that impair UGT1A1 activity. Sequencing of the full gene is also available for detection of variants outside of the TA repeat region. Order UGTI / UDP-Glucuronosyl Transferase 1A1 (UGT1A1), Full Gene Sequencing, Irinotecan Hypersensitivity when evaluating risk for irinotecan toxicity. Order UGT2 / UDP-Glucuronosyl Transferase 1A1 (UGT1A1), Full Gene Sequencing, Hyperbilirubinemia if evaluation for Gilbert syndrome or Crigler-Najjar syndrome type I or type II is desired.