Gilberts Syndrome: UGT1A1 Genotyping

Diagnostic Use

A low-grade non-haemolytic unconjugated hyperbilirubinaemia in the absence of other biochemical or clinical features of hepatic pathology.

Please note: as of September 2024 we are updating the testing method for this condition. Full gene sequencing is being performed by next generation sequencing (NGS). Test pricing is therefore currently under review.

Department

Genetics - Molecular Pathology

Delphic Registration Code

MOLP

Synonyms

hyperbilirubinaemia

Turnaround Time

4 weeks

Test Code

4572

Specimen Type

• Whole Blood
• DNA extract

Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

4.0

No of Samples Required

1

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

1.0

Minimum Sample Volume (ml)

0.5

Additional Specimen Information

This genetic test needs nucleated cells. Please don’t centrifuge or freeze the EDTA blood tube.
If storing blood tube prior to delivery please refrigerate at 4 degrees (transport still at ambient temperature).

Aliquot Instructions

Sample Type

• Whole Blood

Transport to Lab

Ambient (8 - 24 degrees Celsius)

Additional Referral/Aliquot Information

This genetic test needs nucleated cells. Please don’t centrifuge or freeze the EDTA blood tube.
If storing blood tube prior to delivery please refrigerate at 4 degrees (transport at ambient temperature).

An aliquot of DNA extracted by another accredited diagnostic laboratory is also an acceptable sample type. DNA extracts should be 50 ng and of adequate quality for testing with an A260/A280 ratio of 1.8, and an A260/230 ratio greater than 2.0. Please contact the laboratory to discuss specific requirements if the available DNA does not meet these standards.

Interpretation

Gilbert’s syndrome is caused by reduced activity of the uridine diphosphoglucose glucuronyltransferase enzyme (UGT1A1), resulting from the inheritance of two mutant alleles of the gene. It results in low-grade non-haemolytic unconjugated hyperbilirubinaemia, without other biochemical or clinical features of hepatic pathology. In Caucasians, Gilbert’s syndrome is almost exclusively due to the dual inheritance of alleles with a two base insertion in the promoter sequence for the UGT1A1 gene. The TA(7)TAA variant, also referred to as the UGT1A1*28 variant, occurs in the population at a frequency of 30% while the normal TA(6)TAA allele has a frequency of 70%. This leads to a prevalence of Gilbert’s syndrome of approximately 5%.

Test Method

Fluorescently tagged PCR fragments from the UGT1A1 promoter region at 2q37 are accurately sized on the ABI3130xl Genetic Analyser.

Non-Funded Test Cost

$99.21 (Exclusive of GST)

Billing Code

4572

Additional analysis to genotype UGT1A1 *6 and *27 polymorphisms, as well as full DNA sequencing of all coding regions, is also available upon request. This will incur additional charges.

Contact Information

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