DPYD genotyping

Diagnostic Use

5-Fluorouracil (5-FU) is a chemotherapy drug used for a wide variety of cancer treatments. It is metabolised by the dihydropyrimidine dehydrogenase enzyme (DPD). Variants in the DPYD gene, which encodes the DPD enzyme, can cause reduced or abolished DPD activity. When these variants are present, patients are at an increased risk of severe or fatal 5-FU toxicity.

Testing for DPYD variants aids in prediction of toxicity and chemotherapeutic responses.

Delphic Registration Code

MOLP

Laboratory Handling

Phlebotomy

Please do not centrifuge or freeze blood samples. If storing blood tube prior to delivery please refrigerate at 4 degrees (transport at ambient temperature).

Constituent Tests

• Genomic DNA Extraction

Turnaround Time

2 weeks

Test Code

DPYD

Specimen Type

• Whole Blood

Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

4

No of Samples Required

1

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

1

Minimum Sample Volume (ml)

0.5

Pre-testing Requirements

Testing may be prioritized on request and urgent requests will be reported in 5 days.
Please contact us to advise if urgent testing is required.

Additional Specimen Information

Laboratories may prefer to submit DNA for testing. Please provide a minimum of 5 micrograms of DNA at 20 nanograms/microlitre.

This test requires nucleated cells. Please do not centrifuge or freeze blood samples.

If storing blood tube prior to delivery please refrigerate at 4 degrees (transport at ambient temperature).

Aliquot Instructions

Sample Type

• Whole Blood

Transport to Lab

Ambient (8 - 24 degrees Celsius)

Additional Referral/Aliquot Information

This test requires nucleated cells. Please do not centrifuge or freeze blood samples.
If storing blood tube prior to delivery please refrigerate at 4 degrees (transport still at ambient temperature).

Interpretation

The sensitivity and specificity of this test for detecting the 6 DPYD variants specified is 100%.

The frequency of positive results (variants detected) will differ based on the individuals ethnic background. This genotyping panel is expected to give a positive result in up to 8% of individuals with European descent, however a positive result is rarely, if ever, expected in those of east Asian and sub-Saharan African descent (PMID: 30348537, 29152729).

The prevalence of known and novel dysfunctional DPYD variants in the New Zealand population has not currently been assessed. Therefore the reported 25-31% sensitivity of the 6 DPYD variants tested here, for predicting the risk of severe toxicity to 5-FU/capecitabine, may not be accurate/specific to this population.

At this time an accredited phenotyping assay is not available in New Zealand.

Test Method

DYPD testing is performed using a kit designed to identify six variants that are defined in the CPIC guidelines as causing non-functional or reduced function DPD enzyme.

Identified variants are:
- DPYD:c.1679T>G
- DPYD:c.1905+1G>A
- DPYD:c.2846A>T
- DPYD:c.483+18G>A
- DPYD:c.1129-5923C>G
- DPYD:c.1236G>A

These variants have been identified in populations of European origin. Identification of alternative variants will require DPYD sequencing.

Non-Funded Test Cost

$233.20 (Exclusive of GST)

Billing Code

5084

Additional Costing Information

Genomic DNA must be extracted from the specimen prior to testing. This incurs an additional charge (see GDNA).

Laboratories may prefer to submit DNA for testing. Please provide a minimum of 5 micrograms of DNA at 20 nanograms/microlitre.

For full gene sequencing, please refer to Onward Referral for Genetic Testing.

Contact Information

Enquiry Form