Reference Interval:
By report
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| 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.
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| 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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