Ordering Recommendation

Assess genetic risk of abnormal drug metabolism for CYP2C8 and/or CYP2C9 substrates. May aid in drug selection and dose planning for drugs metabolized by CYP2C8 and/or CYP2C9.

Mnemonic
2C8/2C9
Methodology

Polymerase Chain Reaction/Fluorescence Monitoring

Performed

Varies

Reported

5-10 days

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Collect

Whole Blood: Lavender (EDTA), Pink (K2EDTA), or Yellow (ACD Solution A or B).
Saliva:
Collection Device by DNA Genotek (OCD-100, ARUP Supply #49295) available online through eSupply using ARUP Connect™ or by contacting ARUP Client Services at (800) 522-2787.

Specimen Preparation

Transport 3 mL whole blood. (Min: 1 mL) OR Transport the Saliva Collection Device.

Storage/Transport Temperature

Whole Blood: Refrigerated.
Saliva: Room temperature.

Unacceptable Conditions

Plasma or serum. Specimens collected in sodium heparin or lithium heparin.

Remarks
Stability

Whole Blood: Ambient: 72 hours; Refrigerated: 1 week; Frozen: 1 month
Saliva:
Ambient: 2 weeks; Refrigerated: Unacceptable; Frozen: Unacceptable

Reference Interval

By report

Interpretive Data

Background Information for CYP2C8 and CYP2C9:
Characteristics:
The cytochrome P450 (CYP) isozymes 2C8 and 2C9 are involved in the metabolism of many drugs. Variants in the genes that code for CYP2C8 and CYP2C9 may influence pharmacokinetics of substrates, and may predict or explain non-standard dose requirements, therapeutic failure or adverse reactions.
Inheritance:
Autosomal codominant.
Cause:
 CYP2C8 and CYP2C9 gene variants affect enzyme expression or activity.
Variants Tested:
See the "Additional Technical Information" document.
Clinical Sensitivity:
Drug-dependent.
Methodology:
Polymerase chain reaction (PCR) and fluorescence monitoring.
Analytical Sensitivity and Specificity:
Greater than 99 percent.
Limitations:
Only the targeted CYP2C8 and CYP2C9 variants will be detected by this panel, and assumptions about phase and content are made to assign alleles. Publically available sources such as the www.pharmvar.org or www.pharmgkb.org provide guidance on phenotype predictions and allele frequencies. Diagnostic errors can occur due to rare sequence variations. Risk of therapeutic failure or adverse reactions with CYP2C8 or CYP2C9 substrates may be affected by genetic and non-genetic factors that are not detected by this test. This result does not replace the need for therapeutic drug or clinical monitoring. 

Please note the information contained in this report does not contain medication recommendations, and should not be interpreted as recommending any specific medications. Any dosage adjustments or other changes to medications should be evaluated in consultation with a medical provider.

Compliance Statement C: For human genetic inheritable conditions and mutations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Note

Whole blood is the preferred specimen. Saliva samples that yield inadequate DNA quality and/or quantity will be reported as inconclusive if test performance does not meet laboratory-determined criteria for reporting.

Hotline History
N/A
CPT Codes

81227; 81479

Components
Component Test Code* Component Chart Name LOINC
3001502 2C8/2C9 Specimen 31208-2
3001503 CYP2C8 Genotype 78972-7
3001504 CYP2C9 Genotype 46724-1
3001505 2C8/2C9 Interpretation 50398-7
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • 2C8
  • 2C9
  • Coumadin
  • CYP2C8
  • CYP2C9
  • Cytochrome P450 2C8
  • Cytochrome P450 2C9 Genotype
  • glibenclamide
  • gliclazide
  • glimepiride
  • mayzent
  • phenytoin
  • siponimod
  • sulfonylureas
  • tolbutamide
  • warfarin
CYP2C8 and CYP2C9