HLA-B*1502/ Carbamazepine Pharmacogenomic Lab Test
The HLA-B*1502 gene test is used to identify those at risk for serious side-effects to a medication called carbamazepine.
A positive test result means you have the have HLA-B*1502 gene variant and have a higher risk of developing a potentially life-threatening reaction to carbamazepine and should not take this drug. Carbamazepine is not recommended unless the benefit clearly outweighs the risk.
A negative test result means you do not have the HLA-B*1502 gene variant. Carbamazepine may be taken.
HLA-B*1502 Test Results
What should I do with my test results?
Talk to your health care provider or pharmacist about the results. They may suggest that you:
- Keep taking a medication
- Change the dose of a medication
- Stop taking a medication
- Take a different medication
What does my HLA-B*1502 test result mean?
This means that you have the HLA-B*1502 gene variant. A different medication, other than carbamazepine will likely be prescribed. Talk with your health care provider about choosing a medication that is safe for you. For more information, see the Medications.
This means that you do not have the HLA-B*1502 gene variant. Carbamazepine may be prescribed, but this test does not rule out the possibility of all adverse reactions. For more information, see the Medications.
Who will see my results?
Only health care professionals, and those you have given permission, may view your genetic test results. If you are receiving care at another medical facility, Mayo Clinic recommends you share this information with your other healthcare providers.
Which gene affects my response to carbamazepine?
Variants in a gene called the HLA-B can affect how you respond to carbamazepine. The HLA-B gene has hundreds of variations. Each variation is given a number. People with a certain variant in this gene called HLA-B*1502 have a higher risk of developing serious skin reactions, including conditions such as toxic epidermal necrolysis (TEN) and Stevens-Johnson syndrome.
How could the HLA-B* 1502 test result affect my treatment?
If you test positive for the HLA-B*1502 gene variant, you should not take carbamazepine. Your health care provider can help to find an alternative medication that is safe for you.
If you test negative for the HLA-B*1502 gene variant, carbamazepine therapy may be recommended. It is still possible for you to have side effects with carbamazepine even if you do not have the HLA-B*1502 gene variant. If you have a negative test result and take carbamazepine, your health care provider should monitor you routinely for possible side effects.
Who is affected? Do different populations respond differently?
The HLA-B*1502 gene variant is found almost exclusively in individuals with ancestry across broad areas of Asia. Mayo Clinic recommends testing individuals of Asian ancestry before taking carbamazepine.
What is carbamazepine?
Carbamazepine (Tegretol, Carbatrol, Epitol, Equetro, Tegretol-XR, and Teril Suspension) is a drug most often used to treat pain, epilepsy and seizures. It is less commonly used to treat bipolar disorder, schizophrenia and other psychiatric disorders.
Which gene affects my response to carbamazepine?
Variants in a gene called HLA-B can affect how you respond to carbamazepine. The HLA-B gene has hundreds of variations. Each variation is given a number. People with a certain variant in this gene called HLA-B*1502 have a higher risk of developing serious skin reactions, including conditions called toxic epidermal necrolysis (TEM) and Stevens-Johnson syndrome.
What problems can patients with the HLA-B*1502 gene variant have when taking carbamazepine?
Patients with the HLA-B*1502 gene variant can develop toxic epidermal necrolysis or Stevens-Johnson syndrome, which are forms of a rare and serious condition involving the skin and mucous membranes (lining of the mouth and nose).
Toxic epidermal necrolysis is a more serious form of Stevens-Johnson syndrome in which a larger area of the skin or mucous membranes is affected.
Over 90% of patients treated with carbamazepine who develop toxic epidermal necrolysis or Stevens-Johnson syndrome have this reaction within the first few months of treatment. If you are of Asian ancestry and have recently started taking carbamazepine (less than 3 months ago); your health care provider may consider testing you for the HLA-B*1502 gene variant. If you have been taking carbamazepine for more than 3 months without any complications, testing for the HLA-B*1502 gene variant most likely would not be recommended.
The United States Food and Drug Administration (FDA) recommends that patients with Asian ancestry should be tested for the HLA-B*1502 gene variant. Testing individuals of other ancestries is not typically performed.
- Drugs and Supplements – Carbamazepine (Oral Route): Mayoclinic.org
- Information for Healthcare Professionals: Carbamazepine (marketed as Carbatrol, Equerto, Tegretol, and generics): U.S. Food and Drug Administration (FDA)
- Label – Carbamazepine – tablet, extended release: National Institutes of Health (NIH)
Where can I find more information about carbamazepine?
These resources may help you understand more about individualized medicine, genomics and drug-gene testing (pharmacogenomics):
- Mayo Clinic Center for Individualized Medicine
- Cytochrome P450 (CYP450) tests
- Frequently Asked Questions About Pharmacogenomics from National Institutes of Health (NIH) National Human Genome Research Institute
- Table of Pharmacogenomic Biomarkers in Drug Labeling from the U.S. Food and Drug Administration (FDA)
- Genetic Information Nondiscrimination Act
- eMERGE Network: Electronic Medical Records and Genomics
- MyResults.org: Test Results
If you have questions about your test results, ask to speak with your health care provider at your Mayo Clinic care location: