CYP2C9 Gene Coumarin/Warfarin resistance due to CYP2C9 variants NGS Genetic Test
Short Name: CYP2C9 Warfarin Resistance NGS Test
Also known as: CYP2C9 Pharmacogenomic Test, Warfarin Sensitivity Genotyping, CYP2C9 Variant Analysis NGS, Coumarin Resistance Genetic Panel, CYP2C9 Star Allele Test
CYP2C9 Gene Coumarin/Warfarin resistance due to CYP2C9 variants NGS Genetic Test test available at DNA Labs India for ₹20,000. Uses Next-Generation Sequencing (NGS), Sanger Confirmation (if required), Bioinformatics Variant Analysis on Blood or Extracted DNA or One Drop Blood on FTA Card samples. Results in Results are typically available within 3 to 4 weeks from the date of sample collection. Results are delivered online via the DNA Labs India portal, email, and WhatsApp.. Free home collection in 300+ cities across India.
🩺 Medically Reviewed By
Dr SULOCHANA HEMCHANDRA HOLLA
Consultant Medical Geneticist · Reg: 8532
Last reviewed: September 7, 2026
Overview
The purpose of this test is to detect pathogenic and pharmacogenomically relevant variants in the CYP2C9 gene that influence the metabolism of coumarin and warfarin. Identifying a patient's CYP2C9 genotype helps clinicians predict individual drug response, determine appropriate starting doses, avoid adverse bleeding events, and tailor anticoagulant therapy to each patient's genetic profile. This test is particularly valuable for patients who have experienced difficulty achieving therapeutic INR (International Normalized Ratio), unexplained bleeding episodes, or those with a family history of warfarin-related complications.
- Test Code
- 1956
- CPT Code
- 81405
- ICD Code
- Z15.89
- Price
- ₹20,000
- Sample Type
- Blood or Extracted DNA or One Drop Blood on FTA Card
- Result Time
- Results are typically available within 3 to 4 weeks from the date of sample collection. Results are delivered online via the DNA Labs India portal, email, and WhatsApp.
- Fasting Required
- No
- Method
- Next-Generation Sequencing (NGS), Sanger Confirmation (if required), Bioinformatics Variant Analysis
Sample Collection
No special preparation or fasting is required. Patients should inform the healthcare provider about any current medications, recent blood transfusions, or stem cell transplants. A genetic counselling session is recommended prior to sample collection to discuss test purpose, implications, and consent.
Method: Venipuncture / Finger-prick (FTA Card)
Laboratory Analysis
A trained phlebotomist will collect approximately 3 mL of venous blood in an EDTA (lavender-top) vacutainer. Alternatively, a single drop of blood can be spotted on an FTA card. The procedure takes approximately 5-10 minutes. Minimal discomfort may be experienced at the venipuncture site.
Report Delivery
Apply gentle pressure with a cotton ball or gauze at the puncture site for 3-5 minutes. A small bandage may be applied. Avoid heavy lifting or strenuous activity with the collection arm for a few hours. Mild bruising at the site is normal and resolves within a few days. Results will be available in 3 to 4 weeks.
Timeline: Results are typically available within 3 to 4 weeks from the date of sample collection. Results are delivered online via the DNA Labs India portal, email, and WhatsApp.
Patient Instructions
About This Test
Who Should Get This Test
The purpose of this test is to detect pathogenic and pharmacogenomically relevant variants in the CYP2C9 gene that influence the metabolism of coumarin and warfarin. Identifying a patient's CYP2C9 genotype helps clinicians predict individual drug response, determine appropriate starting doses, avoid adverse bleeding events, and tailor anticoagulant therapy to each patient's genetic profile. This test is particularly valuable for patients who have experienced difficulty achieving therapeutic INR (International Normalized Ratio), unexplained bleeding episodes, or those with a family history of warfarin-related complications.
How to Prepare
- No fasting required before sample collection
- Carry a valid photo ID and doctor's prescription or referral
- Inform the phlebotomist about any anticoagulant therapy currently in use
- Provide complete clinical and family history during the pre-test counselling session
- Samples are preferably collected in the morning for same-day dispatch to the laboratory
Doctor's Notes
Reviewed by Dr SULOCHANA HEMCHANDRA HOLLA — MBBS, MD (Medical Genetics) · Reg. No. 8532
"Warfarin remains one of the most widely prescribed anticoagulants in India for conditions such as atrial fibrillation, deep vein thrombosis, pulmonary embolism, and mechanical heart valve prophylaxis. However, the narrow therapeutic index of warfarin, combined with significant inter-individual variability in drug response, makes dosing a clinical challenge. Genetic polymorphisms in the CYP2C9 gene are well-established determinants of warfarin metabolism. Patients carrying CYP2C9*2 or CYP2C9*3 variants typically require lower maintenance doses due to reduced enzyme activity and slower drug clearance, which increases bleeding risk if not accounted for. Conversely, certain rare CYP2C9 variants may confer relative resistance, necessitating higher doses. I recommend CYP2C9 genotyping for all patients initiating warfarin therapy, particularly those with a personal or family history of adverse anticoagulant reactions, difficulty achieving therapeutic INR, or unexplained bleeding events. Integrating pharmacogenomic data into clinical decision-making significantly reduces adverse drug events and improves patient safety."
Last medically reviewed: September 7, 2026
Test Parameters & Specifications
Sample Stability
- Sample received without proper patient identification or requisition form
- Hemolyzed, clotted, or insufficient sample volume
- Sample collected in incorrect anticoagulant or container
- Sample exposed to extreme temperatures during transit
- Leaking or damaged sample container
Understanding Your Results
CYP2C9 *1/*1 (Normal Metabolizer)
Normal response to warfarin anticipated
CYP2C9 *1/*2 or *1/*3 (Intermediate Metabolizer)
Reduced warfarin clearance; increased bleeding risk at standard doses
CYP2C9 *2/*2, *2/*3, or *3/*3 (Poor Metabolizer)
Significantly reduced warfarin clearance; high bleeding risk at standard doses
Rare CYP2C9 Variants (*5, *6, *8, *11, or novel variants)
Variable; specialist interpretation recommended
Variant of Uncertain Significance (VUS)
Insufficient evidence for definitive dosing guidance
Consult your physician or haematologist if you experience unexplained bruising, bleeding gums, blood in urine or stool, prolonged bleeding from cuts, heavy menstrual bleeding, or nosebleeds while on warfarin therapy. Additionally, seek medical advice if your INR is persistently outside the therapeutic range (typically 2.0-3.0), if you are starting warfarin for the first time, or if there is a family history of warfarin-related adverse events. Your doctor may recommend this genetic test to guide personalized anticoagulation therapy.
Limitations
- ⚠This test detects variants in the CYP2C9 gene only and does not assess VKORC1, CYP4F2, or other genes involved in warfarin response
- ⚠Rare or novel variants of uncertain significance (VUS) may be identified; clinical correlation is advised
- ⚠Genetic testing does not replace INR monitoring during warfarin therapy
- ⚠Environmental factors, diet (vitamin K intake), drug interactions, and liver function also influence warfarin dosing
- ⚠Copy number variations (CNVs) may not be fully detected by standard NGS analysis
- ⚠This test is not a substitute for clinical evaluation by a qualified healthcare provider
Risks & Considerations
- ●Minimal risk associated with blood draw: slight pain, bruising, or infection at the venipuncture site
- ●Psychological impact of learning about genetic variants, particularly variants of uncertain significance
- ●Potential insurance or employment discrimination concerns related to genetic information (addressed under Indian genetic data protection guidelines)
- ●False reassurance: normal CYP2C9 genotype does not eliminate all bleeding risks with warfarin therapy
Interfering Factors
- ●Contaminated or degraded DNA sample
- ●Recent blood transfusion within the past 30 days may affect genotyping accuracy
- ●Hemolyzed or improperly stored blood samples
- ●Concurrent medications that strongly inhibit or induce CYP2C9 (e.g., fluconazole, rifampin) may influence clinical interpretation but do not affect genotyping results
- ●Bone marrow or stem cell transplant recipients may have chimeric DNA profiles
Compare With Similar Tests
| Test | CYP2C9 Gene Coumarin/Warfarin resistance due to CYP2C9 variants NGS Genetic Test | VKORC1 Gene Warfarin Sensitivity Test | CYP4F2 Gene Test | Factor V Leiden Mutation Test | Pharmacogenomics Comprehensive Panel |
|---|---|---|---|---|---|
| Comparison | CYP2C9 Gene Coumarin/Warfarin resistance due to CYP2C9 variants NGS Genetic Test | VKORC1 genotyping identifies variants affecting warfarin pharmacodynamics (drug target). Combined CYP2C9 and VKORC1 testing provides the most comprehensive pharmacogenomic profile for warfarin dosing. | CYP4F2 variants (e.g., V433M) influence vitamin K metabolism and can contribute to warfarin dose variability. Often included in expanded pharmacogenomic panels alongside CYP2C9 and VKORC1. | Factor V Leiden is a thrombophilia-related genetic test that identifies a clotting disorder risk factor. It is not directly related to warfarin metabolism but may be relevant in patients with recurrent thrombotic events requiring anticoagulation. | A broader panel that tests multiple drug-metabolizing genes including CYP2C9, CYP2C19, CYP2D6, VKORC1, and others. Useful for patients on multiple medications with potential pharmacogenomic interactions. |
Frequently Asked Questions
What is the CYP2C9 Gene Coumarin/Warfarin Resistance NGS Genetic Test?
Why is CYP2C9 testing important before starting warfarin therapy?
What sample types are accepted for this test?
How long does it take to receive the test results?
Is genetic counselling required before the test?
What are the common CYP2C9 variants tested?
Can this test predict my exact warfarin dose?
Is the test covered by insurance or government health schemes?
Who should consider getting this genetic test?
What is the cost of the CYP2C9 NGS Genetic Test at DNA Labs India?
Is home sample collection available for this test?
What happens if a CYP2C9 variant is detected in my result?
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