Test Details
Methodology
DNA analysis is performed by allele-specific real-time polymerase chain reactions (RT-PCR) to detect single-nucleotide polymorphisms (SNPs) within the DPYD gene and to assign variant DPYDc.1905+1G>A (previously *2A, rs3918290), c.1679T>G (previously *13, rs55886062), c.2846A>T (rs67376798), c.1236G>A (in HapB3 with c.1129-5923C>G, rs56038477), and c.557A>G (rs115232898) alleles. Reference denotes detection of the wild-type sequence at the assessed positions. No other variants in this gene are detected by this assay.
Result Turnaround Time
7 - 10 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Use
The dihydropyrimidine dehydrogenase gene (DPYD) produces a drug-metabolizing enzyme, dihydropyrimidine dehydrogenase (DPD), which is involved in the metabolism of several clinically important drugs including the fluoropyrimidines 5-fluorouracil and capecitabine, which are frequently used as chemotherapeutic drugs. Individuals with some variant DPYD alleles are at increased risk for side effects from drugs that are metabolized by DPD. DPYD genotype information can be utilized to predict DPD metabolic activity, which can be used as an aid in determining a therapeutic strategy for drugs that are metabolized by DPD. For example, DPD eliminates over 80% of the drug 5-fluoracil. An intermediate or poor metabolizer may be subjected to a buildup of 5-fluoracil, which can be associated with severe toxicity. Substantial evidence supports the use of DPYD genotyping for guiding fluoropyrimidine dosage/use.
Variation in the DPYD gene can result in normal (NM), intermediate (IM) and poor (PM) drug-metabolizing genotypes. In general, relative to the reference sequence (normal function), c.2846A>T (rs67376798), c.1236G>A (in HapB3 with c. 1129-5923C>G, rs56038477) and c.557A>G (rs115232898), variants have decreased function while c.1905+1G>A (previously *2A, rs3918290) and c.1679T>G (previously *13, rs55886062) variants have no function.
Limitations
The exact effect of a particular genotype on individual drugs can vary. In addition to genotype, the metabolism of drugs may be influenced by additional factors that include environmental, dietary and other medications; these factors and others should be considered prior to initialing a new therapy. All results must be interpreted in the context of other test results and clinical findings. Results do not rule out the possibility of other variant alleles in DPYD or other variant alleles in other drug metabolism pathways. Patients should speak with their health care provider about the individual results of this test.
Molecular-based testing is highly accurate, but as in any laboratory test, rare diagnostic errors may occur.
This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.
References
Specimen Requirements
Specimen
Whole blood or Labcorp buccal swab kit (buccal swab collection kit contains 4 swabs and instructions for use of a buccal swab)
Volume
2 mL whole blood or one buccal swab kit (4 swabs)
Minimum Volume
1 mL whole blood or two buccal swabs
Container
Lavender-top (EDTA) tube or yellow-top (ACD) tube or Labcorp buccal swab kit
Collection Instructions
Collect specimen in a lavender-top (EDTA) or yellow-top (ACD) tube, or use a buccal swab kit (4 swabs). Ship whole blood specimen at room temperature or frozen. Ship buccal swab kit at room temperature.
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | Whole Blood: 28 days Swabs: 2 Months |
Refrigerated | Whole Blood: 28 days Swabs: Unstable |
Frozen | Whole Blood: 2 years Swabs: Unstable |
Storage Instructions
Maintain whole blood specimen at room temperature or refrigerated for 28 days or frozen for 2 years. Maintain buccal swabs at room temperature for 2 months.
Causes for Rejection
Quantity not sufficient for analysis; improper container; single buccal swab; wet buccal swab; buccal swabs without outer collection envelope; severely damaged buccal swab envelope; buccal swab envelope received open; frozen glass tube
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 512275 | DPYD Genotyping | 93199-8 | 512273 | DPYD Genotype | 93199-8 | |
| 512275 | DPYD Genotyping | 93199-8 | 512274 | DPYD Metabolic Activity | 79719-1 | |
| 512275 | DPYD Genotyping | 93199-8 | 512276 | Director Review | 69426-5 | |
| 512275 | DPYD Genotyping | 93199-8 | 512277 | Interpretation | 56850-1 | |
| 512275 | DPYD Genotyping | 93199-8 | 512278 | DPYD Information | 55752-0 | |
| 512275 | DPYD Genotyping | 93199-8 | 000000 | MGRM Informed Consent Review | N/A | |
| Order Code | 512275 | |||||
| Order Code Name | DPYD Genotyping | |||||
| Order Loinc | 93199-8 | |||||
| Result Code | 512273 | |||||
| Result Code Name | DPYD Genotype | |||||
| UofM | ||||||
| Result LOINC | 93199-8 | |||||
| Order Code | 512275 | |||||
| Order Code Name | DPYD Genotyping | |||||
| Order Loinc | 93199-8 | |||||
| Result Code | 512274 | |||||
| Result Code Name | DPYD Metabolic Activity | |||||
| UofM | ||||||
| Result LOINC | 79719-1 | |||||
| Order Code | 512275 | |||||
| Order Code Name | DPYD Genotyping | |||||
| Order Loinc | 93199-8 | |||||
| Result Code | 512276 | |||||
| Result Code Name | Director Review | |||||
| UofM | ||||||
| Result LOINC | 69426-5 | |||||
| Order Code | 512275 | |||||
| Order Code Name | DPYD Genotyping | |||||
| Order Loinc | 93199-8 | |||||
| Result Code | 512277 | |||||
| Result Code Name | Interpretation | |||||
| UofM | ||||||
| Result LOINC | 56850-1 | |||||
| Order Code | 512275 | |||||
| Order Code Name | DPYD Genotyping | |||||
| Order Loinc | 93199-8 | |||||
| Result Code | 512278 | |||||
| Result Code Name | DPYD Information | |||||
| UofM | ||||||
| Result LOINC | 55752-0 | |||||
| Order Code | 512275 | |||||
| Order Code Name | DPYD Genotyping | |||||
| Order Loinc | 93199-8 | |||||
| Result Code | 000000 | |||||
| Result Code Name | MGRM Informed Consent Review | |||||
| UofM | ||||||
| Result LOINC | N/A |