Thiopurine Methyltransferase (TPMT - *2, *3A, *3B, *3C) Genotyping Test
Also known as: TPMT Genotyping, Thiopurine Methyltransferase Genotyping
Thiopurine Methyltransferase (TPMT - *2, *3A, *3B, *3C) Genotyping Test test available at DNA Labs India for ₹6,000. Uses Sanger Sequencing on Peripheral blood samples. Results in 5-7 days. 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 primary purpose of TPMT genotyping is to determine an individual's genetic predisposition to metabolize thiopurine drugs. By identifying variants associated with low, intermediate, or high TPMT enzyme activity, healthcare professionals can adjust drug dosages accordingly. This helps in preventing adverse drug reactions, improving treatment outcomes, and ensuring patient safety during thiopurine therapy.
- Test Code
- 3230
- Price
- ₹6,000
- Sample Type
- Peripheral blood
- Result Time
- 5-7 days
- Fasting Required
- No
- Method
- Sanger Sequencing
Sample Collection
No special preparation is required. Ensure a doctor's prescription is available if needed.
Method: Venipuncture
Laboratory Analysis
A blood sample will be drawn from a vein in the arm by a trained phlebotomist.
Report Delivery
Apply pressure to the puncture site to prevent bleeding. Resume normal activities.
Timeline: 5-7 days
Patient Instructions
About This Test
Who Should Get This Test
The primary purpose of TPMT genotyping is to determine an individual's genetic predisposition to metabolize thiopurine drugs. By identifying variants associated with low, intermediate, or high TPMT enzyme activity, healthcare professionals can adjust drug dosages accordingly. This helps in preventing adverse drug reactions, improving treatment outcomes, and ensuring patient safety during thiopurine therapy.
How to Prepare
- Fasting is not required.
- Bring a valid ID and doctor's prescription if applicable.
- Inform the collector about any medications or health conditions.
Doctor's Notes
Reviewed by Dr SULOCHANA HEMCHANDRA HOLLA — MBBS, MD (Medical Genetics) · Reg. No. 8532
"TPMT genotyping is crucial for patients on thiopurine drugs to prevent severe side effects like bone marrow suppression. It allows for personalized dosing based on genetic makeup."
Last medically reviewed: September 7, 2026
Test Parameters & Specifications
Sample Stability
- Hemolyzed or clotted sample
- Insufficient sample volume
- Incorrect sample container
Understanding Your Results
Wild Type (Normal)
Normal TPMT enzyme activity. Standard doses of thiopurine drugs are typically safe.
Heterozygous (Intermediate)
Reduced TPMT activity. Consider dose reduction to avoid toxicity.
Homozygous Mutant (Low)
Very low TPMT activity. High risk of severe side effects; alternative therapy or significant dose reduction recommended.
Consult your doctor before starting thiopurine drugs if you have a family history of TPMT deficiency or if you experience side effects like unexplained fever, fatigue, or jaundice during treatment.
Limitations
- ⚠This test only detects specific variants (*2, *3A, *3B, *3C); other rare variants may not be identified.
- ⚠Results should be interpreted in conjunction with clinical history and other laboratory findings.
- ⚠Does not measure actual TPMT enzyme activity; genotyping predicts activity based on genetic variants.
Risks & Considerations
- ●Minimal risk from blood draw, such as slight pain, bruising, or infection at the puncture site.
Interfering Factors
- ●Sample contamination
- ●Improper sample storage
- ●Presence of inhibitors in the sample
Frequently Asked Questions
What is Thiopurine Methyltransferase (TPMT) genotyping?
Why is TPMT genotyping important?
Who should consider TPMT genotyping?
How is the TPMT genotyping test performed?
What do the test results indicate?
Are there any risks associated with the test?
How long does it take to receive the results?
Is home sample collection available for this test?
What is the cost of TPMT genotyping at DNA Labs India?
Can TPMT genotyping be performed on children?
What should I do if my results show a variant?
How accurate is TPMT genotyping?
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