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Test Code 1694339518 Dihydropyrimidine Dehydrogenase, DPYD Genetic Testing

Performing Laboratory

Mayo Clinic Labortatories

Ordering Guidance

Fluoropyrimidines are metabolized primarily by dihydropyrimidine dehydrogenase (DPD), encoded by DPYD. Patients with reduced or absent DPD activity accumulate active drug and are at risk of severe, sometimes fatal toxicity — myelosuppression, mucositis, diarrhea, hand-foot syndrome, and neurotoxicity.

 

DPYDZ and DPYDQ both test for genetic variants in the DPYD gene. DPYDQ test is a targeted genotyping with a faster turnaround (mean of 4 days) time and detects the common variants associated with fluoropyrimidine toxicity. DPYDZ is a full gene sequencing test that detects rare variants in addition to the common variants and has a higher detection rate than DPYDQ test, particularly for individuals of non-European ancestry. DPYDZ test may detect and report variants of uncertain significance and has a slightly longer turnaround time (mean of 7 days).

 

The Association for Molecular Pathology (AMP) Clinical Practice Committee's Pharmacogenomics (PGx) Working Group have defined a minimum set of variant alleles (Tier 1) and an extended list of variant alleles (Tier 2) that may be included in DPYD PGx testing (PMID: 39032821).

 

A comparison of variants detected by the two testing options is provided:

Variant

rsID

AMP Tier

Common allele name

Consequence

Highest multiethnic allele frequency, % (gnomAD v4.1.2)

DPYDQ

DPYDZ

c.557A>G

rs115232898

1

  

Decreased activity

2.1

Yes

Yes

c.1129-5923C>G

rs75017182

1

HapB3

Decreased activity

2.9

Yes

Yes

c.1679T>G

rs55886062

1

∗13

No activity

0.08

Yes

Yes

c.1905+1G>A

rs3918290

1

∗2A

No activity

2.3

Yes

Yes

c.2846A>T

rs67376798

1

  

Decreased activity

0.6

Yes

Yes

c.868A>G

rs146356975

1

  

Decreased activity

0.2

No

Yes

c.2279C>T

rs112766203

1

  

Decreased activity

0.5

No

Yes

c.299_302del

rs72549309

2

∗7

No activity

0.01

Yes

Yes

c.703C>T

rs1801266

2

∗8

No activity

0.03

Yes

Yes

c.1314T>G

rs186169810

2

  

Decreased activity

0.05

No

Yes

c.1475C>T

rs72549304

2

  

No activity

0.02

No

Yes

c.1774C>T

rs59086055

2

  

No activity

0.08

No

Yes

c.2639G>T

rs55674432

2

  

No activity

0.07

No

Yes

c.2983G>T

rs1801268

NA

*10

Decreased activity

<.01

Yes

Yes

 

Because germline DNA results are not expected to change over time, it is generally not recommended to repeat this test. If targeted gene sequencing of the DPYD gene has been previously performed, full gene sequencing may assist with identification of copy number variants in the DPYD gene associated with sensitivity to fluoropyrimidine medications and DPD deficiency.

Specimen Requirements

Specimen Type: Whole blood

Container/Tube:

Preferred: Lavender top (EDTA) or yellow top (ACD)

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send whole blood specimen in original tube. Do not aliquot.

Specimen Stability Information: Ambient 4 days (preferred)/Refrigerated 4 days/Frozen 4 days

Additional Information

  1. Specimens are preferred to be received within 4 days of collection. Extraction will be attempted for specimens received after 4 days, and DNA yield will be evaluated to determine if testing may proceed.
  2. To ensure minimum volume and concentration of DNA are met, the requested volume must be submitted. Testing may be canceled if DNA requirements are inadequate.

Methodology

Sequence Capture and Targeted Next-Generation Sequencing (NGS) followed by Polymerase Chain Reaction (PCR) and Sanger Sequencing

Reference Values

An interpretive report will be provided.

Day(s) Performed

Varies

Report Available: 6 to 10 days

 

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

81232