HLAB*5701

Genetic

Report in 216Hrs

At Home

No Fasting Required

Details

Pharmacogenetic markers.

₹3,552₹5,074

30% OFF

HLA-B*5701 Test Information Guide

Why is it done?
- Detects the presence of the HLA-B*5701 genetic marker, a specific human leukocyte antigen allele associated with increased risk of severe adverse reactions to the antiretroviral medication abacavir
- Screening before initiating abacavir therapy to prevent hypersensitivity reactions (abacavir hypersensitivity syndrome - AHS)
- Identifying HIV-positive patients at high risk for abacavir-related adverse events
- Performed prior to first exposure to abacavir-containing antiretroviral regimens
- Guiding clinical decision-making for alternative antiretroviral therapy selection in patients with positive results
Normal Range
- Negative Result: HLA-B*5701 allele is absent; patient does not carry the genetic marker
- Positive Result: HLA-B*5701 allele is present; patient carries the genetic marker associated with abacavir hypersensitivity
- Units of Measurement: Presence/Absence (qualitative result); reported as positive or negative
- Interpretation: Normal (negative) indicates low risk for abacavir hypersensitivity; abacavir can be safely prescribed. Abnormal (positive) indicates increased risk of severe adverse reactions; abacavir should not be used, and alternative antiretroviral medications should be selected
Interpretation
- Negative Result Interpretation: Patient does not carry the HLA-B*5701 allele and has minimal risk of abacavir hypersensitivity syndrome; abacavir can be prescribed without concern for this specific genetic predisposition
- Positive Result Interpretation: Patient carries the HLA-B*5701 allele and has significantly elevated risk (approximately 50% or higher) of developing abacavir hypersensitivity syndrome; abacavir is contraindicated and should be avoided
- Clinical Significance of Abacavir Hypersensitivity Syndrome: Can manifest as fever, rash, gastrointestinal symptoms, respiratory symptoms, and constitutional symptoms; typically occurs within first 6 weeks of therapy; can be life-threatening if rechallenge occurs after initial reaction
- Factors Affecting Results: Ethnic and racial variation in allele frequency (higher prevalence in Caucasian, Hispanic, and Native American populations); lower prevalence in African, Asian, and Pacific Islander populations
- Importance of Pre-treatment Testing: FDA recommends testing before initiating abacavir; testing is more cost-effective than managing hypersensitivity reactions; prevents potentially life-threatening adverse events
Associated Organs
- Primary System Involved: Immune system; HLA-B*5701 is part of the major histocompatibility complex (MHC) class I molecules expressed on cell surfaces
- Organs Affected by Abacavir Hypersensitivity Reaction: Skin (rash), respiratory system (shortness of breath, cough), gastrointestinal tract (nausea, vomiting, diarrhea, abdominal pain), liver (elevated transaminases), lymph nodes (lymphadenopathy), heart (in severe cases)
- Associated Medical Conditions: HIV infection requiring antiretroviral therapy; abacavir hypersensitivity syndrome; immune-mediated drug reactions
- Potential Complications from Abnormal Result: Severe hypersensitivity reaction if abacavir is inadvertently prescribed; anaphylaxis with rechallenge after initial reaction; hospitalization; death in rare cases if reaction is severe or untreated
- Immune Mechanism: HLA-B*5701 presents abacavir metabolites to T cells, triggering CD8+ T cell-mediated immune response causing delayed hypersensitivity reaction
Follow-up Tests
- For Negative Results: No additional HLA-B*5701 testing required; proceed with abacavir prescription if clinically indicated; standard HIV monitoring tests (CD4 count, viral load) continue
- For Positive Results: Consultation with HIV specialist or pharmacist for alternative antiretroviral regimen selection; baseline CD4 count and viral load if not recently obtained; assess patient's current antiretroviral therapy
- Complementary Tests for HIV Management: CD4+ T cell count; HIV-1 viral load; Resistance testing (genotype/phenotype); Other HLA testing if considering other medications with HLA associations (HLA-DRB1 and HLAB*5701 for additional abacavir confirmation, HLA-B*5801 for allopurinol)
- If Hypersensitivity Suspected: Complete blood count; liver function tests; Clinical reassessment; Discontinuation of abacavir immediately if suspected
- Ongoing Monitoring: Regular HIV-related appointments; Drug interaction screening when new medications considered; Patient education on avoiding abacavir if positive result
Fasting Required?
- Fasting Requirement: No - Fasting is not required for HLA-B*5701 testing
- Sample Collection: Blood sample collected via venipuncture into EDTA (purple top) anticoagulant tube; typically 5-10 mL of whole blood required; can be collected at any time of day
- Patient Preparation: No special preparation needed; patient may eat and drink normally; no fasting required; can be performed regardless of meal timing
- Medications: No medications need to be withheld; continue all prescribed medications as usual; HLA typing is not affected by medications; note that abacavir should NOT be started pending test results
- Important Timing Consideration: Test should be performed BEFORE starting abacavir therapy; if abacavir was already initiated, discontinue immediately if HLA-B*5701 positive
- Specimen Handling: Keep sample at room temperature or refrigerated until processing; transport to laboratory promptly; test results typically available within 1-2 weeks depending on laboratory

How our test process works!