Warfarin Genotyping Plus
2004358
Ordering Recommendation
This is the preferred test if individualized warfarin dosage planning is required. Warfarin Sensitivity (CYP2C9 and VKORC1) 3 Mutations test is performed and individualized dosing recommendations are provided when specific patient parameters are submitted. Clinical utility has not been established.
Mnemonic
WARF PLUS
Methodology
Polymerase Chain Reaction/DNA Hybridization/Electrochemical Detection
Performed
Mon, Thu
Reported
5-7 days  
New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
  
Collect
Lavender (EDTA) or pink (K2EDTA).  
Specimen Preparation
Transport 3 mL whole blood. (Min: 1 mL)  
Storage/Transport Temperature
Refrigerated.  
Unacceptable Conditions
  
Remarks
  
Stability
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable  
Reference Interval
By report  
Interpretive Data
Background Information for Warfarin Genotyping Plus:
Characteristics:
Warfarin overdosing can result in life-threatening events, e.g., bleeding. This test does not identify patients at risk for warfarin resistance.
Incidence:
Up to 1 percent mortality and 15 percent morbidity due to bleeding complications.
Cause:
Mutations in the CYP2C9 and VKORC1 genes. The common CYP2C9 gene mutations (*2 and *3) with the VKORC1 gene promoter mutation (c.-1639G>A), are estimated to account for 40-63 percent of the variability in therapeutic warfarin dose.
Mutations Tested:
CYP2C9 *2 (c.430C>T), CYP2C9 *3 (c.1075A>C), VKORC1 (c.-1639G>A).
Allele Frequencies:
CYP2C9 *2, 0.08-0.13, 0.02-0.06, and less than 0.01; CYP2C9 *3, 0.06-0.10, less than 0.1, and 0.01-0.04; VKORC1 (c.-1639G>A), 0.42, 0.89, and 0.08 in Caucasian, Asian, and African-American populations, respectively. Other populations are less well characterized. The VKORC1 (c.-1639G>A) is in very strong linkage disequilibrium with the VKORC1 (c.173+1000C>T).
Clinical Sensitivity:
90 percent of CYP2C9 and VKORC1 mutations causing warfarin sensitivity in Caucasians are detected. Less characterized in other populations.
Methodology:
Polymerase chain reaction, DNA hybridization, and Electrochemical Detection
Analytical Sensitivity and Specificity:
99 percent.
Limitations:
Mutations other than those targeted will not be detected; analytical sensitivity may be compromised by rare primer or probe site mutations. Diagnostic errors can occur due to rare sequence variations.





See Compliance Statement C: www.aruplab.com/CS
Statement C: The performance characteristics of this test were validated by ARUP Laboratories. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test; however, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. ARUP is authorized under Clinical Laboratory Improvement Amendments (CLIA) and by all states to perform high-complexity testing.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
 
Note
This test generates a customized patient report that provides the clinician with estimated daily and weekly maintenance warfarin doses for the individual patient.  However, the following patient information is REQUIRED as input data for the proprietary multivariate mathematical algorithm (PerMIT): 
- INR target
- Nicotine use? Y/N
- Amiodarone co-administration? Y/N
- Height in inches
- Weight in pounds

If this patient information is not provided, the Warfarin Sensitivity (CYP2C9 & VKORC1) 3 Mutations (ARUP test code 0051370), which does not have a customized patient report, WILL BE SUBSTITUTED.
CPT Code(s)
81227, 81355
Components
Component Test Code*Component Chart Name
0051237CYP2C9 Variant
0051238CYP2C9 Variant
0051371VKORC1 Allele 1
0051372VKORC1 Allele 2
2004334Warfarin Plus - Amiodarone , Y/N
2004335Warfarin Plus - Nicotine Use, Y/N
2004337Warfarin Plus - Height in Inches
2004338Warfarin Plus - INR, Target
2004368Warfarin Plus - Specimen
2004369Warfarin Plus - Weight in Pounds
2004370Warfarin Plus - Interpretation
2004371EER Warfarin Genotyping Plus
* 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
  • Warfarin Sensitivity Genotyping