TPMT (thiopurine S-methyltransferase), NUDT15 (nudix hydroxylase 15) (eg, thiopurine metabolism) gene analysis, common variants (ie, TPMT *2, *3A, *3B, *3C, *4, *5, *6, *8, *12; NUDT15 *3, *4, *5)
CPT4 code
Name of the Procedure:
Thiopurine S-methyltransferase (TPMT) and Nudix Hydroxylase 15 (NUDT15) Gene Analysis
Common variants include TPMT *2, *3A, *3B, *3C, *4, *5, *6, *8, *12 and NUDT15 *3, *4, *5.
Summary
This procedure analyzes specific genetic variants in the TPMT and NUDT15 genes, which play a crucial role in the metabolism of thiopurine drugs. These drugs are often used in the treatment of leukemia, autoimmune disorders, and inflammatory bowel disease. The analysis helps to identify the risk of toxicity and to optimize drug dosage.
Purpose
The analysis is primarily used to:
- Predict the patient's reaction to thiopurine drugs.
- Prevent severe side effects by tailoring the drug dosage according to the patient's genetic makeup.
- Ensure effective treatment while minimizing complications.
Indications
- Patients about to begin thiopurine drug therapy.
- Individuals experiencing adverse reactions or ineffective results from thiopurine drugs.
- Patients with a family history of thiopurine sensitivity or related genetic variations.
Preparation
- No specific fasting or dietary restrictions are required.
- Inform the healthcare provider about any medications currently being taken.
- A simple blood test or saliva sample is used for the analysis.
Procedure Description
- Sample Collection: A blood or saliva sample is collected from the patient.
- DNA Extraction: The sample is processed in the laboratory to extract DNA.
- Gene Analysis: The DNA is analyzed for the presence of common TPMT and NUDT15 variants using specialized techniques like polymerase chain reaction (PCR).
- Results Interpretation: The results are reviewed by a genetic specialist to determine the appropriate thiopurine dosage.
Duration
The sample collection takes a few minutes. Laboratory analysis typically takes about 1-2 weeks.
Setting
The sample collection can be performed in a hospital, outpatient clinic, or specialized laboratory.
Personnel
- Phlebotomist or nurse for sample collection.
- Laboratory technicians and geneticists for DNA analysis.
- Physician or genetic counselor to interpret the results.
Risks and Complications
- Minimal risk associated with blood sample collection, such as slight discomfort or bruising at the puncture site.
- Rare instances of infection or dizziness.
Benefits
- Personalized thiopurine therapy with optimized dosage.
- Reduced risk of drug toxicity and related side effects.
- More effective treatment outcomes.
Recovery
- No significant recovery time required.
- Patients can resume normal activities immediately after sample collection.
Alternatives
- Empirical dosage adjustments based on patient response and side effects, though this is less precise.
- Use of alternative medications if thiopurine drugs are unsuitable based on genetic testing results.
Patient Experience
- Minimal discomfort during sample collection (similar to a routine blood draw).
- No need for anesthesia or sedation.
- Assurance through personalized treatment planning and potential relief from adverse drug reactions.
By undergoing TPMT and NUDT15 gene analysis, patients can achieve more effective and safer thiopurine drug therapy, tailored to their genetic profile.