Warfarin Sensitivity (CYP2C9 and VKORC1 ) 3 Mutations
0051370
 
Ordering Recommendation
Aids in warfarin dosage planning. If individualized dosing recommendations are required, refer to Warfarin Genotyping Plus (2004358).
Mnemonic
WARF GENO
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 Sensitivity (CYP2C9 and VKORC1) 3 Mutations:
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.



Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.

See Compliance Statement C: www.aruplab.com/CS
Note
CPT Code(s)
81227, 81355
Components
Component Test Code*Component Chart Name
0051237CYP2C9 Variant
0051238CYP2C9 Variant
0051371VKORC1 Allele 1
0051372VKORC1 Allele 2
0051373Warfarin Sensitivity Interpretation
2001336Warfarin Sensitivity - Specimen
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, contact interface support at interface.support@aruplab.com.
Cross References
  • Warfarin Sensitivity Genotype by Sequence Analysis, Saliva (Warfarin Sensitivity (CYP2C9 and VKORC1 ) 3 Mutations)