Improved equity of DPYD testing

DPYD testing is recommended prior to initiating fluoropyrimidine-based treatment. Our reports include the following variants/haplotypes:

• Genetic variants already included in testing, [NT1] c. 1905+ 1G>A, c.1679T>G, c.2846A>T and HapB3.
• A newly mandated variant (c.557A>G) aligned to 2024 UK SACT board guidance (opens in a new tab) and known to be more prevalent in non-European populations.

A full table of variants reported is included at the end of the page

When assessing DPYD results, we encourage you to always check the UK SACT board website for updated guidance.

The inclusion of the additional variant means testing will identify more patients with intermediate or poor metaboliser phenotypes. The result should be used alongside current clinical guidance to inform dose adjustments or recommendations for other suitable therapies.

No change to prescribing pathways is required, but clinicians should review test results carefully before initiating treatment.

Find out about ordering DPYD pharmacogenomic testing

What the UK SACT guidance includes

The UK SACT Board have updated their dosing guidelines (opens in a new tab) for fluoropyrimidines in the context of DPYD variation. Please update any local guidance in accordance with this.

The guidance includes:

• evidence for the c.557A>G (African prevalence) variant
• National DPYD best practice pathway
• Detail on HapB3 haplotype and linkage disequilibrium

Significance of the c.557A>G variant

The inclusion of this variant helps to improve equity of testing across ethnic groups, testing has previously been most effective in patients originating from European populations.

The updated panel and guidance incorporates variants associated with fluoropyrimidine toxicity in African, Asian and other under-represented populations. Expanding the variant panel improves detection of patients at risk of severe toxicity across diverse ethnic backgrounds. This helps reduce inequity in pharmacogenomic screening and supports safer, more personalised dosing for all patients.

What this means for practice

• The updated test improves risk assessment across ethnic groups, but testing remains recommended for all patients, regardless of ethnicity.
• Ethnicity alone should not guide dosing decisions; results from the expanded DPYD panel should inform management alongside clinical judgement and existing guidelines.

The NHS target turnaround time for DPYD testing continues to be five calendar days.