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Test Name:
Warfarin Sensitivity (CYP2C9 and VKORC1), 3 Mutations
- SBMF No:
44809 - Performance Lab Name:
ARUP Laboratories - Test Mnemonic:
WARF-GENO - ABN:
Required – Not FDA-Approved - CPT Code:
83891; 83896x3; 83898x3; 83912 - LOINC Code:
56164-7; 19146-0; 19146-0; 19146-0; 19146-0; 19146-0 - Ref Lab Test No:
0051370 - Also Known As:
Pharmacogenomic Testing for Warfarin Response - Also See:
45286 Cytochrome P450 2C9 (CYP2C9), 2 Mutations - Spec Type:
Whole blood - Spec Container:
Lavender top (EDTA) tube - Pref Vol:
3.0 mL - Min Vol:
1.0 mL - Fasting:
No - Patient Prep:
Counseling and informed consent are recommended for genetic testing
Forms required:
Informed Consent for Molecular Genetic Testing
Patient History for Molecular Genetic Testing - Spec Collect:
Routine venipuncture - Spec Process:
Gently invert tube to mix blood with the anticoagulant
Do not centrifuge
Do not remove plasma from cells
Forward entire tube of unprocessed whole blood to the laboratory - Spec Store Transport:
Refrigerated - Spec Stability:
72 hours room temperature (20-30°C)
1 week refrigerated (2-8°C)
Frozen (-20°C): Unacceptable - Spec Reject:
Frozen specimen - Methodology:
Polymerase Chain Reaction (PCR)
Fluorescence Monitoring - Clinical Significance:
Refer to:
- Reference Range:
By Report
Interpretive Data:
Background Information for Warfarin Sensitivity (CYP2C9 & 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 0.01, 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 followed by unlabeled probe and melting curve analysis.
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 - Additional Test Info:
Genetic Compliance Statement: 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 form are available online.
- Day Run:
Mon, Thu - Time Reported:
6-8 days - Test Type:
GENETIC
