Test ID: HLA15
HLA-B 1502 Genotype, Carbamazepine Hypersensitivity
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Identifying individuals of Asian ancestry who are at risk of developing Stevens-Johnson syndrome and toxic epidermal necrolysis when administered carbamazepine, phenytoin, or fosphenytoin therapy
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Allele-Specific Polymerase Chain Reaction (PCR) Amplification
(PCR is utilized pursuant to a license agreement with Roche Molecular Systems, Inc.)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Carbamazepine Hypersensitivity
Fosphenytoin Hypersensitivity
HLA-B
HLAB 1502
Phenytoin Hypersensitivity
SJS
Stevens-Johnson Syndrome, Carbamazepine, Phenytoin, or Fosphenytoin
Toxic Epidermal Necrosis (TEN), Carbamazepine, Phenytoin, or Fosphenytoin
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Multiple whole blood EDTA genotype tests can be performed on a single specimen after a single extraction. See Multiple Whole Blood EDTA Genotype Tests in Special Instructions for a list of tests that can be ordered together.
Container/Tube: Lavender top (EDTA)
Specimen Volume: 3 mL
Collection Instructions: Send specimen in original tube.
Additional Information: Transfusions will interfere with testing for up to 4 to 6 weeks. DNA obtained from white cells may not provide useful information for patients who received a recent transfusion of blood that was not leukocyte-reduced. Wait 4 to 6 weeks until transfused cells have left the patient's circulation before drawing the patient's blood specimen for genotype testing.
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 (Supply T576) is available in Special Instructions.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Whole Blood EDTA | Ambient (preferred) | |
| Refrigerated | ||
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Clinical studies have demonstrated associations between some human leukocyte antigen (HLA) genotypes and drug-induced adverse skin reactions. The presence of the HLA-B*1502 allele increases the risk of developing toxic epidermal necrolysis (TEN) or Stevens-Johnson syndrome (SJS), a milder form of TEN. The frequency of the HLA-B*1502 allele varies throughout Asia: 10% to 15% frequency in Chinese, 2% to 4% frequency in Southeast Asians, including Indians, and <1% frequency in Japanese and Koreans.
The Food and Drug Administration (FDA) recommends that individuals of Asian ancestry be genotyped for the presence of the HLA-B*1502 allele prior to receiving:
-carbamazepine, a drug used to treat epilepsy, manic/bipolar disorders, and neuropathic pain
-phenytoin and its soluble precursor fosphenytoin, drugs used to control seizures
Some studies have also suggested a connection between HLA-B*1502 positivity and adverse reactions to lamotrigine used for treating epilepsy and bipolar disorder.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
An interpretive report will be provided.
Interpretation Provides information to assist in interpretation of the test results
Positivity for human leukocyte antigen (HLA)-B*1502 confers increased risk for hypersensitivity to carbamazepine, phenytoin, or fosphenytoin.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
In patients who have had a recent transfusion, genotyping using DNA obtained from white blood cells may not provide useful information; wait 4 to 6 weeks until transfused cells have left the circulation.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Man CB, Kwan P, Baum L, et al: Association between HLA-B*1502 allele and antiepileptic drug-induced cutaneous reactions in Han Chinese. Epilepsia 2007;40:1015-1018
2. Chung WH, Hung SL, Hong HS, et al: Medical genetics: a marker for Stevens-Johnson syndrome. Nature 2004;428:486
3. Hung SL, Chung WH, Jee SH, et al: Genetic susceptibility to carbamazepine-induced cutaneous adverse drug reaction. Pharmacogenet Genomics 2006;16:297-306
4. Cox ST, McWhinnie AJ, Robinson J, et al: Cloning and sequencing full-length HLA-B and -C genes. Tissue Antigens 2003;61:20-48
5. Hung, Shuen-Iu. Chung, Wen-Hung. Liu, Zhi-Sheng. Chen et al: Common risk allele in aromatic antiepileptic-drug induced Stevens-Johnson syndrome and toxic epidermal necrolysis in Han Chinese. Pharmacogenomics. 2010;11:349-356
Method Description Describes how the test is performed and provides a method-specific reference
The assay, modified from Man et al (2007), consists of 5 multiplexed allele-specific PCR amplifications of HLA-B regions with detection following electrophoresis. (Man CB, Kwan P, Baum L, et al: Association between HLA-B*1502 allele and antiepileptic drug-induced cutaneous reactions in Han Chinese. Epilepsia 2007;40:1015-1018)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Tuesday, Friday
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
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 Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 89347 | HLA-B 1502 Result | 57979-7 |
| 29317 | HLA-B 1502 Interpretation | 69047-9 |
| 29318 | HLA-B 1502 Reviewed by | In Process |
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