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UGT1A1 Genotype

Published: July 27, 2026Updated: August 25, 2026

The UGT1A1 genotype is a pharmacogenomic biomarker that determines how efficiently the UGT1A1 enzyme metabolizes certain drugs and toxins, particularly irinotecan.

Quick summary

UGT1A1 genotype predicts the risk of adverse reactions to medications like irinotecan.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
genotype
Clinical utility
predictive
Result kind
qualitative
FDA-cleared
Roche UGT1A1, Abbott UGT1A1, Esoterix UGT1A1
interpretation: {"text":"Patients with normal UGT1A1 activity are expected to metabolize UGT1A1 substrates efficiently, with a typical risk of adverse reactions.","label":"Normal Activity"}; {"text":"Individuals with reduced UGT1AA1 activity may require dose adjustments or alternative medications to avoid toxicity.","label":"Reduced Activity"}

The UGT1A1 gene encodes the uridine diphosphate glucuronosyltransferase 1A1 enzyme, which plays a crucial role in the metabolism of substances like bilirubin and various drugs, including the chemotherapy agent irinotecan.

Variations in the UGT1A1 gene, such as the *28 allele, can lead to reduced enzyme activity, affecting the rate at which drugs are metabolized and potentially increasing the risk of adverse reactions.

Testing for UGT1A1 genotype can help clinicians tailor medication dosages or choose alternative treatments to minimize toxicity and improve patient outcomes.

Frequently asked questions

What is the clinical significance of UGT1A1 genotyping?
UGT1A1 genotyping helps predict an individual's response to certain medications, allowing for personalized treatment plans that minimize adverse effects.
How is UGT1A1 genotyping performed?
UGT1A1 genotyping is typically done using PCR-based methods to detect specific genetic variations associated with enzyme activity.
  1. 1
    UGT1A1 Genotyping in Irinotecan TherapySource
  2. 2
    Pharmacogenomics of UGT1A1 and Irinotecan ToxicitySource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy