Additional Information:
Epic order code: LAB5169
CPT Code(s):
81225
Specimen Requirements:
Collect at least 3 mL of blood in:
- EDTA: Lavender-top tube;
- K2EDTA: Pink-top tube; or
- ACD Solution A or B: Yellow-top tube.
Severely hemolyzed, clotted and/or frozen blood specimens, and specimens in heparin (green-top) tubes are not accepted.
Specimen Preparation: Transport 3 mL of whole blood. (minimum 1 mL)
Storage/Transport Temperature: Refrigerated
Stability (collection to initiation of testing):
- Ambient: 72 hours
- Refrigerated: 1 week
- Frozen: Unacceptable
Use:
This test identifies the CYP2C19 genotype to determine the patient's rate of metabolism for drugs activated or inactivated by this pathway. It has particular importance in metabolizing the drug clopidogrel (Plavix®).
Methodology:
Real-time polymerase chain reaction-based/fluorescence-monitoring test
Reported:
7-10 days
Reference Values:
No allelic variants detected (*1/*1)
Performed:
Monday - Friday
Interpretation Data:
Analytical Interpretation: The report includes the patient's diplotype of CYP2C19 genes and is reported using star alleles as follows:
- *1/*1 for no allelic variant present; or
- *17/*17 for a homozygous c.991A>G genotype (which has increased function).
| CYP2C19 Allelic Variants Tested | |||
|---|---|---|---|
| Allele | Nucleotide | Effect | Predicted Enzyme Activity |
| *1 | No allelic variant | Normal | Normal |
| *2 | c.681G>A | Splicing defect | Non-functional |
| *3 | c.636G>A | New stop codon | Non-functional |
| *4 | c.1A>G | Loss of initiation | Non-functional |
| *5 | c.1297C>T | R433W | Non-functional |
| *6 | c.395G>A | R132Q | Non-functional |
| *8 | c.358T>C | W120R | Non-functional |
| *10 | c.680C>T | P227L | Decreased function |
| *17 | c.991A>G | Increased transcription | Increased function |
Clinical Interpretation: The clinical significance of the result along with recommendations for therapy will be provided.
- Normal metabolism
- Impaired metabolism
- Very imparied metabolism
- Enhanced metabolism
- Unknown effect on metabolism
- Indeterminate result