Cytochrome P450 2C19 (CYP2C19) Genotyping
Test Code
Cytochrome P450 2C19 (CYP2C19)
CPT Codes
83891 x1; 83892 x2; 83900 x1; 83901 x3; 83914 x7; 83909 x1; 83912 x1; 83912-25 x1
Specimen
Whole blood, buccal swabs or saliva
Volume
5 mL of whole blood, four buccal swabs or 1mL saliva
Minimum Volume
3 mL of whole blood, four buccal swabs or 1mL saliva
Container
Lavender-stopper (EDTA) tube, paper envelope for dried buccal swabs, 1mL saliva collection tube
Storage Instructions
Maintain at room temperature or refrigerate
Cause for Rejection
Hemolyzed specimen; quantity not sufficient
Use
CYP2C19 metabolizes approximately 10% of all drugs, including Plavix© (clopidogrel), citalopram, diazepam, and many of the proton pump inhibitors. Detecting variants of the CYP2C19 gene that cause altered enzymatic activity can identify patients who may be at increased risk of having adverse drug reactions or therapeutic failure to standard dosages of CYP2C19 substrates.
Limitations
Other variants of the CYP2C19 gene that are not detected in this assay may influence drug metabolism. CYP2C19 metabolic capacity is also influenced by concomitant medications, inhibitors, inducers, diet and various disease states. All factors should be considered as part of the overall patient management strategy.
Methodology
Multiplex polymerase chain reaction and allele-specific primer extension (Tag-It (TM)).
Turnaround Time
Five business days after receipt of specimen. STAT turnaround time of 3 business days is available for an additional charge.
