UGT1A1 TA Repeat Genotype (Sendout)

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General Information

Lab Name
UGT1A1 TA Repeat Genotype (Sendout)
Lab Code
RU1A1G
Epic Ordering
UGT1A1 TA Repeat Genotype (Sendout)
External Test Id
U1A1Q
Description

Useful For:

  • Identifying individuals who are at increased risk of adverse drug reactions with drugs that are metabolized by UGT1A1; especially irinotecan but also atazanavir, nilotinib, pazopanib, and belinostat
  • Identifying individuals with Gilbert syndrome due to the presence of homozygous UGT1A1*6 (NM_000463.2:c.211G>A) allele, TA7, homozygous TA8, or compound heterozygous *6, TA7 or TA8
  • Identifying individuals who are carriers of Gilbert syndrome due to the presence of heterozygous TA7 or TA8
  • This test is not useful for assessment of Crigler-Najjar syndrome.
References
  1. Mayo Clinical & Interpretive Information: UDP-Glucuronosyltransferase 1A1 TA Repeat Genotype, UGT1A1
Synonyms
GNT1, Irinotecan metabolism, Phenol/Bilirubin UDP-Glucuronosyltransferase, U1A1Q, UDP-Glucosyltransferase 1, UGT1A1, UGT1A1 Genotype, Uracil Glucuronyl transferase, Uridine Diphosphate Glucosyltransferase 1
Components

Interpretation

Method

Real-Time Polymerase Chain Reaction (PCR) with Allelic Discrimination Analysis

Reference Range
See individual components
Ref. Range Notes

An interpretive report will be provided.

Interferences and Limitations

Advisory: This test does not detect or report variants other than the *1 (TA6), *28 (TA7), *36 (TA5), and *6 (NM_000463.2:c.211G>A) alleles. The *37 (TA8) allele cannot be distinguished from *28 (TA7) and will be reported as *28 (TA7) by this methodology. Numerous variants outside of the TA repeat region have been described that impair UGT1A1 activity.

Cautions: Samples may contain donor DNA if obtained from patients who received non-leukoreduced blood transfusions or allogeneic hematopoietic stem cell transplantation. Results from samples obtained under these circumstances may not accurately reflect the recipient's genotype. For individuals who have received blood transfusions, the genotype usually reverts to that of the recipient within 6 weeks. For individuals who have received allogeneic hematopoietic stem cell transplantation, a pretransplant DNA specimen is recommended for testing.

UGT1A1 genetic test results in patients who have undergone liver transplantation may not accurately reflect the patient's UGT1A1 status.

Liver or renal dysfunction may result in adverse drug reactions with irinotecan independently of thymine-adenine (TA)-repeat variants.

References
  1. Mayo Clinical & Interpretive Information: UDP-Glucuronosyltransferase 1A1 TA Repeat Genotype, UGT1A1

Ordering & Collection

Specimen Type
Blood
Collection

3 mL blood in LAVENDER TOP (EDTA) tube

Handling Instructions

Outside Laboratories: Transport whole blood at room temperature.

Stability: Ambient (Preferred): 9 days; Refrigerated: 30 days; Frozen: Unacceptable.

Quantity
requested: 3 mL EDTA whole blood
minimum: 0.4 mL EDTA whole blood

Processing

Processing

Store whole blood at room temperature in Sendouts ambient rack.

Sendouts:

  • Order Test: U1A1Q.
  • Interfaced: Yes.

Stability: Ambient (Preferred): 9 days; Refrigerated: 30 days; Frozen: Unacceptable.

Performance

LIS Dept Code
Sendouts Mayo Lab (AB) (MAAB)
Performing Location(s)
Sendout Mayo Clinic Laboratories
800-533-1710

200 First Street Southwest
Rochester, MN 55901
Frequency
Performed: Monday - Friday. Report available: 3-6 days.
Available STAT?
No

Billing & Coding

CPT codes
81350
LOINC
34509-0