DPYD

Drugs affected by DPYD

Dihydropyrimidine Dehydrogenase

2 medications 5 brand products

About DPYD

DPYD breaks down fluoropyrimidine chemotherapy drugs (5-FU, capecitabine).^[1] A small percentage of people carry reduced-function variants that cause the drug to accumulate to toxic levels. This is one of the few pharmacogenetic tests that is mandatory in many oncology guidelines before starting treatment.^[2]

Partial DPYD deficiency calls for a 25 to 50 percent dose reduction. Complete deficiency is a contraindication: standard-dose fluoropyrimidine can be fatal.^[3]

What we test for DPYD

Gene2Rx uses definitions covering 28 named DPYD alleles, built from 28 variants in Gene2Rx definitions. Results depend on the variants available in your upload.

Named alleles

Defined variants

Gene2Rx definitions

Source

GRCh38

Genome build

Normal Function 1 Decreased Function 6 No Function 21

Notable DPYD alleles

Reference Normal Function

No tested DPYD variants — typical DPD enzyme activity expected.

c.1905&1G>A No Function

A no-function splice-site variant strongly associated with fluoropyrimidine toxicity.

~1% in Europeans

c.1679T>G No Function

A no-function variant (also called *13) linked to severe fluoropyrimidine adverse events.

c.2846A>T Decreased Function

A decreased-function missense variant; carriers warrant a fluoropyrimidine dose reduction.

What do these allele names mean?

DPYD alleles are named by the underlying DNA variant rather than a star number. For example, c.61C>T describes a single base change at position 61 of the coding sequence.

DNA variant labels identify sequence differences. Their interpretation depends on the particular gene, the evidence, and the variants that can be assessed in your data. A DNA result does not directly measure enzyme activity.

The source of these definitions is listed above. Missing variants or incomplete coverage can leave a result indeterminate.

Medications with DPYD information

This list contains 2 medications with DPYD information from the sources shown below. Evidence and report eligibility differ by drug; each page explains its scope and limitations.

chemotherapies →

Capecitabine CPIC / FDA Fluorouracil CPIC / FDA

Brand products containing a DPYD-affected ingredient

These branded medications include at least one active ingredient whose metabolism or action involves DPYD. Each links to its full pharmacogenetic breakdown.

References

CPIC. CPIC Guideline for Fluoropyrimidines and DPYD (2017). cpicpgx.org
U.S. Food and Drug Administration. Table of Pharmacogenomic Biomarkers in Drug Labeling (2024). fda.gov
PharmGKB / Stanford University. PharmGKB: The Pharmacogenomics Knowledge Base. pharmgkb.org

Explore DPYD in your report

A Gene2Rx report interprets supported variants in the context of your data and purchased report. Missing or uncertain calls may prevent an assessment.

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Informational only, not medical advice. The presence of a DPYD pharmacogenetic guideline does not mean every patient needs to change their dose. Never start, stop, or change a medication without talking to your prescribing clinician.