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Test ID: HL57O HLA-B 5701 Genotype, Abacavir Hypersensitivity, Saliva

Reporting Name

HLAB 5701 Abacavir Genotype, Saliva

Useful For

Identifying individuals with an increased risk of hypersensitivity reactions to abacavir, based on the presence of the HLA-B*57:01 allele

 

Genotyping patients who prefer not to have venipuncture done

Testing Algorithm

See Abacavir Hypersensitivity Testing and Initial Patient Management Algorithm in Special Instructions

Specimen Type

Saliva


Specimen Required


Multiple saliva genotype tests can be performed on a single specimen. See Multiple Saliva Genotype Tests in Special Instructions for a list of tests that can be ordered together.

 

Container/Tube: Oragene DNA Self-Collection Kit (T651: fees apply)

Specimen Volume: Full tube

Collection Instructions:

1. Fill tube to line.

2. Send specimen in original container per kit instructions.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Saliva Ambient

Reference Values

An interpretive report will be provided.

Day(s) and Time(s) Performed

Monday, Wednesday through Friday; 10 a.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

81381-HLA Class I typing, high resolution (ie, alleles or allele groups); one allele or allele group (eg, B*57:01P), each

LOINC Code Information

Test ID Test Order Name Order LOINC Value
HL57O HLAB 5701 Abacavir Genotype, Saliva 42358-2

 

Result ID Test Result Name Result LOINC Value
33022 HLA-B 5701 Result 42358-2
33024 HLA-B 5701 Interpretation 69047-9
33023 HLA-B 5701 Reviewed by No LOINC Needed

Clinical Information

The human leukocyte antigen (HLA) genes help the immune system recognize and respond to foreign substances (such as viruses and bacteria). The HLA-B gene encodes a class 1 HLA molecule in the major histocompatibility complex (MHC), which acts by presenting peptides to immune cells. There are more than 1,500 different HLA-B alleles identified, one of which is the HLA-B*57:01 allele. Frequency of the HLA-B*57:01 allele varies with ethnicity, with a frequency of 6% to 7% in European populations, and up to 20% in Southwest Asian populations.

 

The HLA-B*57:01 allele has been associated with hypersensitivity to abacavir, a highly effective nucleoside analog reverse-transcriptase inhibitor used to treat HIV infection and AIDS. Per the Clinical Pharmacogenomics Implementation Consortium (CPIC) dosing guidelines for abacavir and HLA-B, individuals who are positive for the HLA-B*57:01 allele are at an increased risk for abacavir hypersensitivity and it is not recommended for use in treating these individuals.

 

Hypersensitivity reactions, which generally occur during the first 6 weeks of treatment, are often nonspecific and include skin rashes, gastrointestinal symptoms (eg, nausea, vomiting, diarrhea, and abdominal pain), and respiratory symptoms. Fatalities have been reported with abacavir hypersensitivity. Prospective testing for the HLA-B*57:01 genotype and excluding HLA-B*57:01-positive individuals from treatment with abacavir decreases the incidence of abacavir hypersensitivity.

 

See Abacavir Hypersensitivity Testing and Initial Patient Management Algorithm in Special Instructions.

Interpretation

Positivity for human leukocyte antigen allele HLA-B*57:01 confers high risk for hypersensitivity to abacavir.

 

See Abacavir Hypersensitivity Testing and Initial Patient Management Algorithm in Special Instructions.

 

For additional information regarding pharmacogenomic genes and their associated drugs, see the Pharmacogenomic Associations Tables in Special Instructions. This resource also includes information regarding enzyme inhibitors and inducers, as well as potential alternate drug choices.

Clinical Reference

1. Saag M, Balu R, Brachman P, et al: High sensitivity of HLA-B*5701 in whites and blacks in immunologically-confirmed cases of abacavir hypersensitivity. Fourth IAS Conference on HIV Pathogenesis, Treatment, and Prevention. July 22-25, 2007. Sydney. Abstract WEAB305)

2. Martin M, Klein T, Dong B, et al: Clinical Pharmacogenetics Implementation Consortium Guidelines for HLA-B Genotype and Abacavir Dosing. Clin Pharmacol Ther 2012;91(4):734-738

3. Martin M, Hoffman J, Freimuth R, et al: Clinical Pharmacogenetics Implementation Consortium Guidelines for HLA-B Genotype and Abacavir Dosing: 2014 update. Clin Pharmacol Ther 2014;95(5):499-500

4. Faruki H, Heine U, Brown T, et al: HLA-B*5701 clinical testing: early experience in the United States. Pharmacogenet Genom 2007;17:857-860

5. Sun HY, Hung CC, Lin PH, et al: Incidence of abacavir hypersensitivity and its relationship with HLA-B*5701 in HIV-infected patients in Taiwan. J. Antimicrob Chemother 2007;60:599-604

Analytic Time

1 day (not reported Saturday or Sunday)

Method Name

Qualitative Allele-Specific Real-Time Polymerase Chain Reaction (PCR)

Forms

New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (T576) is available in Special Instructions.

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

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