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HLA-B*5701 GENOTYPING

Item Value
Test code B57RT
Performed by? Chemistry
Price range $$$
In House Availability Once a week
Principle Real-time polymerase chain reaction (RT-PCR) and fluorescence monitoring for detection of the HCP5 single-nucleotide polymorphism (SNP), rs2395029, which is in perfect linkage disequilibrium with the HLA-B*5701 allele.
Interpretation Abacavir sulfate, or Ziagen(R), is a nucleoside reverse-transcriptase inhibitor with potent antiviral activity against HIV. Approximately 5% of individuals being treated with abacavir develop a potentially life-threatening hypersensitivity reaction. Several studies have identified a strong genetic association between human leukocyte antigen (HLA) B5701 allele and an increased risk of abacavir hypersensitivity, in the Caucasian population. Pharmacogenetic screening for the HLA B5701 allele is recommended prior to initiation of abacavir therapy.
Container type EDTA (lavender top) tube
Amount to Collect 4 mL
Sample type Serum
Preferred volume 4 mL whole blood
Normal range Results are reported as Negative, Heterozygous or Homozygous.

A NEGATIVE result indicates that the HCP5 SNP (rs2395029) was not detected in the patient, therefore the patient is negative for HLA-B*5701. A negative result for HLA-B*5701 does not preclude the development of an allergic response to abacavir. The HLA-B*5701 results should not substitute for appropriate clinical vigilance and patient management in abacavir containing regimens. Administration of abacavir therapy requires close observation including immediate discontinuation of therapy should signs or symptoms of hypersensitivity develop.

A HETEROZYGOUS result indicates that one copy of the HLA-B*5701 allele was detected; therefore, the patient is at significantly increased risk for abacavir hypersensitivity. Avoidance or discontinuation of abacavir is strongly advised.

A HOMOZYGOUS result indicates that two copies of the HLA-B*5701 allele were detected; therefore, the patient is at significantly increased risk for abacavir hypersensitivity. Avoidance or discontinuation of abacavir is strongly advised.
Synonyms HLA-B5701; B*5701; b57; hla B57; hla antigen B*5701; Abacavir hypersensitivity
Turn around times 2 weeks
References 1. Phillips E, Mallal S. Drug Hypersensitivity in HIV. Curr Opin Allergy Clin Immunol. 2007 Aug; 7(4):324-30.

2. Mallal S, Nolan D, Witt C, et al. Association between presence of HLA-B*5701, HLA-DR7, and HLA-DQ3 and hypersensitivity to HIV-1 reverse-transcriptase inhibitor abacavir. Lancet. 2002 Mar 2; 359(9308):727-732.

3. Hetherington S, Hughes AR, Mosteller M, et al. Genetic variations in HLA-B region and hypersensitivity reactions to abacavir. Lancet. 2002 Mar 30; 359(9312):1121-1122.

4. Hughes AR, Mosteller M, Bansal A, et al. Association of genetic variations in HLA-B region with hypersensitivity to abacavir in some, but not all, populations. Pharmacogenomics. 2004 Mar 5; 5(2):203-211.

5. Zucman D, Truchis P, Majerholc C, Stegman S, Caillat-Zucman S. Prospective screening for human leukocyte antigen-B*5701 avoids abacavir hypersensitivity reaction in the ethnically mixed French HIV population. J Acquir Immune Defic Syndr. 2007 May 1; 45(1):1-3.

6. Rauch A, Nolan D, Martin A, McKinnon E, Almeida C, Mallal S. Prospective genetic screening decreases the incidence of abacavir hypersensitivity reactions in the Western Australian HIV cohort study. Clin Infect Dis. 2006 Jul 1; 43(1):99-102.

7. Martin AM, Krueger R, Almeida CA, Nolan D, Phillips E, Mallal S. A sensitive and rapid alternative to HLA typing as a genetic screening test for abacavir hypersensitivity syndrome. Pharmacogenet Genomics. 2006 May;16(5):353-7.
CPT coding multiple CPTs
Last Updated 5/13/2014 4:40:26 PM
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