HLA-B*58:01 Genotyping, Allopurinol Hypersensitivity

Casandra

Casandra Test Code AR29361Version 1 (DRAFT)

Performing Lab

Lab ARUP LaboratoriesLab Test ID 3001393CPT Code 81381

HLA-B*58:01 Genotyping, Allopurinol Hypersensitivity

Also known as: HLA B5801

Clinical Use

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Use

The HLA-B*58:01 genotyping test is designed to identify patients at increased risk for severe cutaneous adverse reactions (SCAR) to allopurinol, a drug commonly used to treat hyperuricemia and gout. SCAR includes conditions like Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), which can be life-threatening. The presence of the HLA-B*58:01 allele shows a strong association with allopurinol-induced SCAR, leading to recommendations for testing before initiating allopurinol therapy. Due to the severe nature of SCAR, which has a high mortality rate, identifying the allele can guide safer use of allopurinol, particularly in populations with higher allele frequencies.

Special Instructions

Patients with a positive result for the HLA-B*58:01 allele should avoid allopurinol due to the increased risk for severe adverse reactions. Alternative medication should be considered as first-line therapy. Monitoring for symptoms of SJS or TEN is crucial, and therapy should be discontinued immediately if symptoms develop.

Limitations

The test only identifies the presence of the HLA-B*58:01 allele and does not provide information about other genetic or non-genetic factors influencing allopurinol hypersensitivity. Copy number variations of HLA-B*58:01 are not reported. Other rare or novel alleles may yield false positive or negative results, and additional clinical factors should be considered in conjunction with test results.

Test Details

New York Approved