Days Set Up
Monday - Thursday
Analytic Time

2 - 7 days

MiChart Code
UGT1A1 Promoter Genotyping
Soft Order Code
UGT

Test Updated:

Synonyms

Gilbert Syndrome
Uridine Diphosphate Glucuronyltransferase 1A1 Promoter Genotyping
UGT1A1
UGT
MLABEL
UGT1A1S
UGT1A1 Promoter Genotyping PCR
Irinotecan Sensitivity Analysis

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MLabs provides all the supplies necessary for the collection of specimens.

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Test Overview

Test Methodology

Polymerase Chain Reaction (PCR) with capillary electrophoresis

Test Usage

Irinotecan, also known as Camptosar® or CPT-11, is an anti-neoplastic agent used to treat colorectal cancers. Uridine diphosphate glucuronyltransferase 1A1 (UGT1A1) is responsible for the metabolic inactivation of SN-38 (active form of Irinotecan) via glucuronidation. Individuals with low levels of UGT1A1 activity are at increased risk for toxicity following Irinotecan administration, due to the presence of elevated levels of unconjugated SN-38. Decreased UGT1A1 activity can result from mutations in the coding sequence of the UGT1A1 gene, which alter the structure of the encoded protein, or from decreased expression of the normal protein product. A common cause of decreased expression levels of UGT1A1 is a variation in the number of TA repeats in the TATA box of the UGT1A1 gene promoter. The (TA)6 (i.e., 6 TA repeats) version of the promoter is considered to be the "normal" or wild type. Compared to the (TA)6 promoter, the (TA)7 version has a decreased activity, leading to the production of lower levels of UGT1A1 transcripts. To date, alleles containing 5, 6, 7, and 8 TA repeats have been identified. Several clinical studies have shown that individuals who are homozygous, and potentially those who are heterozygous, for the UGT1A1 (TA)7 promoter allele (UGT1A1*28) are at increased risk for the development of a significant adverse response to the standard dose of Irinotecan. Therefore, in July of 2005, the FDA altered the package labeling of Irinotecan to suggest a lower starting dose of Irinotecan for patients known to be homozygous for the UGT1A1 *28 (i.e., 7 TA repeat) allele.

Reference Range

Interpretive report provided.

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Specimen Requirements

Collection Onsite

Collect blood in a lavender top tube. Refrigerate and send intact blood or bone marrow specimen within 48 hours of collection.

Collection Offsite

Collect blood in a lavender top tube. Refrigerate and send intact blood or bone marrow specimen within 48 hours of collection.

Lavender Top Tube
Normal Volume
5 mL EDTA (lavender) whole blood. Extracted DNA is also acceptable if extracted in a CLIA certified laboratory.
Minimum Volume
 

Billing Information

CPT Code
81350
Pro Fee Code
 
LOINC
 

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Our High Standard

Quality that sets us apart

As the reference laboratory division of Michigan Medicine's Department of Pathology, MLabs shares the institution's commitment to applying established quality principles to clinical laboratory testing. Like other large organizations in complex, consequential fields, we rely on an established approach to monitor quality throughout the testing process.