Use of test
A specific variant of the human leukocyte antigen B15, HLA-B*15:02, is associated with severe cutaneous adverse reactions (SCAR) to the medication, carbamazepine. This variant occurs more commonly in people of Han Chinese ancestry than in other ethnic groups. The pharmaceutical manufacturer recommends that this test be performed before prescribing carbamazepine
HLA-A*31:01 has similar but less strong predictive value in Caucasians. If a person has this genotype and has been on carbamazepine for more than three months, they are unlikely to develop SCAR.
This test has a role in identifying patients who may benefit from avoiding a specific drug or dose, but it provides little useful information for people (including relatives) who are not taking the medications of concern. Testing of relatives is generally not recommended.
The presence of this variant indicates that a person is at increased risk of severe cutaneous adverse reaction (SCAR) to carbamazepine.
This is an assay for heritable variants which can alter the probability that a person will develop a disorder. The test result is not, in isolation, diagnostic of a disease and the test result is not necessarily clinically significant for the patient's relatives.
Analysis of the gene sequence of the HLA-B genes for the presence of this specific variant.
Requesting the test
This test can be requested by any medical practitioner.
5 mL blood in EDTA. Specimens may be collected by the requesting practitioner or at any Sonic Healthcare pathology collection centre.
To help ensure the quality of the test, a genetic test should be done with a dedicated sample whenever possible i.e. a sample collected specifically for that test rather than a sample that is used for multiple tests.
We recommend that the patient or another adult check the labelling of request forms and sample tubes.
5 business days.
This test is not rebated by Medicare. The laboratory assumes that the patient or client has provided informed financial consent for the test.