Test Catalog

Test Id : CARBR

Carbamazepine Hypersensitivity Pharmacogenomics, Varies

Useful For
Suggests clinical disorders or settings where the test may be helpful

Identifying individuals with increased risk of risk of carbamazepine- or oxcarbazepine-associated cutaneous adverse reactions

Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request

Detection of the HLA-B*15:02 allele (HLA00165) in the HLA-B gene (NM_005514).

 

Detection of the HLA-A*31:01 allele (HLA00097) in the HLA-A gene (NM_001242758).

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

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

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Carbamazepine PGx Panel, V

Aliases
Lists additional common names for a test, as an aid in searching

Carbamazepine Hypersensitivity

HLA A

HLA A31

HLA A3101

HLA B

HLA B15

HLA B1502

HLAA 3101

HLAB1502

Oxcarbazepine Hypersensitivity

Pharmacogenetic

Pharmacogenomic

Phenytoin Hypersensitivity

SJS

Stevens-Johnson Syndrome

Toxic Epidermal Necrosis (TEN)

Specimen Type
Describes the specimen type validated for testing

Varies

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Multiple genotype tests can be performed on a single specimen after a single extraction. See Multiple Genotype Test List in Special Instructions for a list of tests that can be ordered together. 

 

Submit only 1 of the following specimens:

 

Specimen Type: Whole blood

Container/Tube: Lavender top (EDTA)

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send specimen in original tube.

Specimen Stability Information: Ambient (preferred) 9 days/Refrigerated 30 days

 

Specimen Type: Saliva

Supplies: Saliva Swab Collection Kit (T786)

Patient Preparation: Patient should not eat, drink, smoke, or chew gum 30 minutes prior to collection.

Specimen Volume: 1 swab

Collection Instructions: Collect and send specimen per kit instructions.

Specimen Stability Information: Ambient 30 days

 

Specimen Type: Extracted DNA

Container/Tube: 2 mL screw top tube

Specimen Volume: 100 mcL (microliters)

Collection Instructions:

1. The preferred volume is 100 mcL at a concentration of 50 ng/mcL.

2. Include concentration and volume on tube.

Specimen Stability Information: Frozen (preferred) 1 year/Ambient/Refrigerated

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Forms

1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. If not ordering electronically, complete, print, and send 1of the following forms with the specimen:

-Therapeutics Test Request (T831)

-Neurology Specialty Testing Client Test Request (T732)

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.35 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Varies Varies (preferred)

Useful For
Suggests clinical disorders or settings where the test may be helpful

Identifying individuals with increased risk of risk of carbamazepine- or oxcarbazepine-associated cutaneous adverse reactions

Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request

Detection of the HLA-B*15:02 allele (HLA00165) in the HLA-B gene (NM_005514).

 

Detection of the HLA-A*31:01 allele (HLA00097) in the HLA-A gene (NM_001242758).

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Carbamazepine and oxcarbazepine are aromatic anticonvulsants, as are eslicarbazepine, lamotrigine, phenytoin, fosphenytoin, and phenobarbital. Carbamazepine is FDA-approved for the treatment of epilepsy, trigeminal neuralgia, and bipolar disorder. Oxcarbazepine is FDA-approved for the treatment of partial seizures. A minority of carbamazepine- or oxcarbazepine-treated persons have cutaneous adverse reactions that vary in prevalence and severity, with some forms associated with substantial morbidity and mortality. The most severe reactions, such as the Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), are characterized by a blistering rash affecting a variable percentage of the body-surface area. TEN is the rarest of these phenotypes and is associated with mortality of up to 30%. Drug reaction with eosinophilia and systemic symptoms (DRESS) and maculopapular exanthema (MPE) may also be related to carbamazepine exposure. According to the FDA-approved label for carbamazepine, the estimated incidence of SJS-TEN is 1 to 6 cases in 10,000 persons of European ancestry who are exposed to the drug. The rate of SJS-TEN as a result of carbamazepine exposure is about 10 times higher in some Asian countries. According to the FDA label for oxcarbazepine, the rate of TEN and SJS among individuals exposed to oxcarbazepine exceeds the background incidence by a factor of 3- to 10-fold, but this is expected to be an underestimate due to underreporting.

 

Clinical studies have demonstrated associations between some human leukocyte antigen (HLA) genotypes and drug-associated cutaneous adverse reactions. The presence of the HLA-B*15:02 allele varies throughout Asia: 10% to 15% frequency in Chinese; 2% to 4% frequency in Southeast Asians and Indians; and less than 1% frequency in Japanese and Koreans. This allele is strongly associated with greater risk of SJS and TEN in patients treated with carbamazepine or oxcarbazepine and has also been associated with SJS/TEN with phenytoin use. There is very limited evidence associating SJS/TEN/DRESS or MPE and other aromatic anticonvulsants in patients who are positive for HLA-B*15:02.

 

The HLA-A*31:01 allele, which has a prevalence of 2% to 5% in Northern European populations, 6% among Hispanic/South American populations, and 8% among Japanese populations, has been significantly associated with greater risk of MPE, DRESS, and SJS/TEN among patients treated with carbamazepine. In the absence of HLA-A*31:01, the risk for drug-associated cutaneous adverse reactions is 3.8%, but in the presence of this allele, the risk increases to 26%. The evidence linking other aromatic anticonvulsants with SJS/TEN in the presence of the HLA-A*31:01 allele is weaker; however, an alternative medication should be chosen with caution.

 

The FDA-approved label for carbamazepine states that the screening of patients in genetically at-risk populations (ie, patients of Asian descent) for the presence of the HLA-B*15:02 allele should be carried out prior to initiating treatment with carbamazepine. The FDA-approved label also notes the association of HLA-A*31:01 allele with drug-associated cutaneous adverse reactions regardless of ethnicity, but it does not specifically mandate screening of patients. The FDA-approved label for oxcarbazepine indicates that testing for the presence of the HLA-B*15:02 allele should be considered in patients with ancestry including genetically at-risk populations prior to initiation of therapy.

 

According to the most recent Clinical Pharmacogenetic Implementation Consortium (CPIC) guideline, patients who are HLA-B*15:02 positive should not be prescribed carbamazepine or oxcarbamazepine if alternative agents are available; however, caution should be used in selecting an alternative medication as there is weaker evidence that also links other aromatic anticonvulsants with SJS/TEN in patients positive for HLA-B*15:02. Furthermore, phenytoin is the subject of a separate CPIC guideline with recommendations to avoid phenytoin in HLA-B*15:02 positive individuals, along with additional recommendations based on CYP2C9 genotype. Patients who are HLA-A*31:01 positive should not be prescribed carbamazepine if alternative agents are available. However, although very limited evidence links SJS/TEN/DRESS/MPE with other aromatic anticonvulsants, among HLA-A*31:01-positive patients, caution should be used in selecting an alternative medication.

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

The presence of the HLA-B*15:02 and/or HLA-A*31:01 allele confers increased risk for hypersensitivity to carbamazepine. The presence of the HLA-B*15:02 allele also confers increased risk for hypersensitivity to oxcarbazepine and phenytoin.

 

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.

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Rare reported or unreported HLA-A and HLA-B alleles may occur and may interfere with this assay, resulting in a false-positive or false-negative call. Examples of alleles that may interfere include other HLA-A*31 alleles (including HLA-A *31:01:23), HLA-B*15:13, HLA-B*15:31, HLA-B*15:55, HLA-B*15:88, HLA-B*15:89, HLA-B*18:20, HLA-B*15:112, HLA-B*15:121, HLA-B*15:144, and HLA-B*15:170. However, most of these alleles are rare and exist only in specific ethnicities, and it is not known if any of these subtypes are associated with hypersensitivity. For example, HLA-B*15:13, while rare, has been observed more in Asian populations than other populations.

 

Samples may contain donor DNA if obtained from patients who received non-leukoreduced blood transfusions or allogeneic hematopoietic stem cell transplantation (AHSCT). Results from samples obtained under these circumstances may not accurately reflect the recipient's genotype. For individuals who have received blood transfusions, the genotype usually reverts to that of the recipient within 6 weeks. The impact of AHSCT on risk of adverse cutaneous reactions is not defined in the literature.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Phillips EJ, Sukasem C, Whirl-Carrillo M, et al: Clinical Pharmacogenetics Implementation Consortium guideline for HLA genotype and use of carbamazepine and oxcarbazepine: 2017 Update. Clin Pharmacol Ther. 2018;103(4):574-581

2. Caudle KE, Rettie AE, Whirl-Carrillo M, et al: Clinical pharmacogenetics implementation consortium guidelines for CYP2C9 and HLA-B genotypes and phenytoin dosing. Clin Pharacol Ther. 2014;96(5):542-548

3. McCormack M, Alfirevic A, Bourgeois S, et al: HLA-A*3101 and carbamazepine-induced hypersensitivity reactions in Europeans. N Engl J Med. 2011;364:1134-1143

4. Amstutz U, Shear NH, Rieder MJ, et al: Recommendations for HLA-B*15:02 and HLA-A*31:01 genetic testing to reduce the risk of carbamazepine-induced hypersensitivity reactions. Epilepsia. 2014;55:496-506

5. Caudle KE, Rettie AE, Whirl-Carrillo M, et al: Clinical Pharmacogenetics Implementation Consortium Guidelines for CYP2C9 and HLA-B genotypes and phenytoin dosing. Clin Pharmacol Ther. 2014;96(5):542-548

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

Genomic DNA is extracted from whole blood. Amplification for the HLA-B*15:02 and HLA-A*31:01 alleles and an internal control gene is performed by real-time polymerase chain reaction (PCR) in the presence of SYBR Green, which fluoresces when bound to double-stranded DNA. A genotype is assigned based on the allele-specific SYBR Green fluorescent signals that are detected.(Unpublished Mayo method)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday, Wednesday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

1 to 5 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

Whole Blood/Saliva: 2 weeks; Extracted DNA: 2 months

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

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 instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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 US Food and Drug Administration.

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 Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

81381 x 2

LOINC® Information

Test Id Test Order Name Order LOINC Value
CARBR Carbamazepine PGx Panel, V 94855-4
Result Id Test Result Name Result LOINC Value
Result LOINC Value Tooltip
610657 HLA-A*31:01 Genotype 79712-6
610658 HLA-B*15:02 Genotype 57979-7
610659 Carbamazepine PGx Panel Phenotype 93308-5
610660 Interpretation 69047-9
610661 Additional Information 48767-8
610662 Method 85069-3
610663 Disclaimer 62364-5
610664 Reviewed by 18771-6

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports