ARUP's Laboratory Test Directory

Warfarin Sensitivity (CYP2C9 & VKORC1 ) 3 Mutations : 0051370

Mnemonic: WARF GENO

Methodology: Polymerase Chain Reaction/Fluorescence Monitoring
Performed: Mon, Thu
Reported: 5-7 days
Specimen Required: Collect:  One 3 mL lavender (EDTA) or pink (K2EDTA).

Transport:  3 mL whole blood at 2-8°C.  (Min: 1 mL)

Pediatric Collection/Transport:  1 mL whole blood at 2-8°C.

Stability:  Ambient: 3 days; Refrigerated: 1 week; Frozen: Unacceptable
Reference Interval:
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 Detected:
 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

This test is performed pursuant to an agreement with Roche Molecular Systems, Inc.





Please refer to Statement C in the Compliance Statements section in the front of the Laboratory Test Directory.
CPT Code(s): 83891 Isolation; 83898 x3 Amplification; 83896 x3 Nucleic acid probes; 83912 Interpretation and report. Additional CPT code modifiers may be required for procedures performed to test for oncologic or inherited disorders
 
 

 

 

 
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