Gene Polymorphism TA (UGT1A1)

GENE POLYMORPHISM TA (UGT1A1)

The UGT1A1 Gene Polymorphism (TA Repeat) Test is a genetic test used to identify variations in the promoter region of the UGT1A1 gene, specifically the number of TA repeats. This gene is responsible for producing an enzyme that helps process bilirubin in the liver.

Certain polymorphisms, such as increased TA repeats, can reduce enzyme activity and lead to conditions like Gilbert’s syndrome, which is characterized by mild, intermittent elevations in bilirubin levels. This test is also important in pharmacogenomics, as UGT1A1 variations can affect how the body metabolizes certain medications, particularly some chemotherapy drugs.

The purpose of this test is to:

• Detect UGT1A1 gene polymorphisms (TA repeats)
• Diagnose conditions like Gilbert’s syndrome
• Assess bilirubin metabolism disorders
• Support pharmacogenomic evaluation for drug metabolism
• Guide personalized treatment decisions

GENE POLYMORPHISM TA (UGT1A1) Test

The UGT1A1 TA Polymorphism test is a genetic test that identifies variations in the UGT1A1 gene, particularly differences in the number of TA repeats in the promoter region. UGT1A1 produces an enzyme involved in the metabolism of bilirubin and certain medicines.

The most commonly evaluated variant is UGT1A1*28, which contains seven TA repeats, compared with six repeats in the common *1 allele. Increased numbers of TA repeats can reduce UGT1A1 enzyme activity. When present in two copies, this variant may be associated with Gilbert syndrome, a generally benign condition characterized by intermittent elevation of unconjugated bilirubin.

The test is also clinically useful in pharmacogenetic evaluation before irinotecan treatment. Individuals with reduced UGT1A1 activity may have a higher risk of certain irinotecan-related toxicities, including severe neutropenia and diarrhea. Genotyping can therefore help healthcare professionals consider treatment and dosing decisions alongside the patient's overall clinical condition.

GENE POLYMORPHISM TA (UGT1A1) Test is Recommended for Individuals:

• Individuals being evaluated for Gilbert syndrome
• People with unexplained or recurrent unconjugated hyperbilirubinemia
• Individuals with intermittent jaundice without an obvious liver disorder
• Patients with suspected inherited differences in bilirubin metabolism
• Cancer patients who are being considered for irinotecan therapy
• Individuals requiring pharmacogenetic assessment before treatment with medicines metabolized by UGT1A1
• Patients with a family history suggestive of Gilbert syndrome
• Individuals whose healthcare provider recommends UGT1A1 genotyping

FAQs

1. What does the UGT1A1 TA Polymorphism test detect?
It detects variations in the number of TA repeats in the promoter region of the UGT1A1 gene. The commonly evaluated *28 variant contains seven TA repeats and can reduce UGT1A1 expression.

2. Is the UGT1A1 test used for Gilbert syndrome?
Yes. UGT1A1 genetic testing can support the evaluation of Gilbert syndrome, particularly when there is persistent or intermittent unconjugated bilirubin elevation and other causes have been excluded.

3. Why is UGT1A1 testing important before irinotecan treatment?
UGT1A1 helps metabolize the active irinotecan metabolite SN-38. Certain UGT1A1 variants can reduce enzyme activity and may increase the risk of serious treatment-related toxicity. Testing can therefore provide useful information for treatment planning.