UGT1A1 Gene Polymorphism (TA Repeat)

Casandra

Casandra Test Code QD44514Version 1 (DRAFT)

Performing Lab

Lab Quest DiagnosticsLab Test ID 17813CPT Code 81350

UGT1A1 Gene Polymorphism (TA Repeat)

Also known as: Irinotecan Toxicity, Colorectal Cancer (CRC), Irinotecan Metabolism, Gilbert's Syndrome, UPD-glucuronosyltransferase 1A1 (UGT1A1)

Clinical Use

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Use

This test is intended to identify patients who may have Gilbert syndrome and those who are at increased risk for irinotecan toxicity due to UGT1A1 TA‑repeat promoter variants; variants in the TA repeat region influence bilirubin metabolism and SN‑38 detoxification by UGT1A1, informing risk for adverse drug reactions (e.g., neutropenia, diarrhea) and guiding therapeutic management.

Special Instructions

Not provided.

Limitations

This assay does not detect other variants or mutations in the UGT1A1 gene that may impair irinotecan metabolism, nor does it examine other genetic or non‑genetic modifiers. Individuals with two copies of TA7 have a higher risk for side effects. It is a genotyping test targeting only TA repeats and does not distinguish TA7 vs TA8 (both reported as TA7).

Test Details