Sign in →

Test ID HTR2 Serotonin Receptor Genotype (HTR2A and HTR2C)

Useful For

Guiding treatment choice of a selective serotonin reuptake inhibitor (SSRI) or non-SSRI antidepressant

 

Guiding treatment choice in individuals who have a drug-metabolizer phenotype discordant with CYP450 genotypes

 

Identifying patients who may benefit from treatment with the antipsychotic drug clozapine and aripiprazole

 

Identifying those patients at risk of excessive weight gain when receiving antipsychotic medications

Method Name

Polymerase Chain Reaction (PCR) with Allele-Specific Primer Extension (ASPE)

(PCR is utilized pursuant to a license agreement with Roche Molecular Systems, Inc.)

Reporting Name

Serotonin Receptor 2A/2C Genotype

Specimen Type

Whole Blood EDTA

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

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

0.3 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole Blood EDTA Ambient (preferred)
  Refrigerated 

Clinical Information

Treatment with specific antidepressant and antipsychotic medications is often guided empirically. Despite the wide array of drugs available for treatment, some patients do not initially respond to treatment, and others who respond early may eventually relapse or develop serious side effects. Antidepressant selection may be more effectively guided by genotyping polymorphic genes encoding several cytochrome P450 enzymes, the serotonin transporter, and the serotonin (5-hydroxytryptamine) receptors HTR2A and HTR2C.(1)

 

Drugs that bind to the serotonin receptors have a wide range of effects including altering the activation of the receptors, rendering them more or less sensitive to drug concentration, or blocking the receptor. Variations (polymorphisms) in the genes that encode for the serotonin receptor have been associated with different types of drug responses including:

-Allelic variation in the HTR2A gene has been reported to affect response to selective serotonin reuptake inhibitors (SSRI) and risk for adverse drug reactions.(2) Patients predicted to respond poorly to SSRIs due to polymorphic variants in the HTR2A/2C serotonin receptors may be considered for switching to non-SSRI antidepressants. Allelic variations in the HTR2A gene has been linked with response to the antipsychotic drugs clozapine and aripiprazole.(3)

-Treatment with antipsychotics results in significant weight gain (2-3 kg/m[2]) in some patients. Weight gain has been positively correlated with a polymorphism in the promoter of HTR2C (-759C).(4)

 

Allele nomenclature:

Gene

Nucleotide Change

Amino Acid Change

HTR2A

-1438G>A

Promoter polymorphism

HTR2A

74C>A

Thr25Asp

HTR2A

IVS2+54538A>G

Non-coding

HTR2A

1354C>T

His452Tyr

HTR2C

-759C>T

Promoter polymorphism

Reference Values

An interpretive report will be provided.

Cautions

Patients who have received a heterologous blood transfusion within the preceding 6 weeks, or who have received an allogeneic blood or marrow transplant, can have inaccurate genetic test results due to presence of donor DNA.

 

Drug-drug interactions must be considered when dealing with heterozygous individuals.

 

This test does not detect polymorphisms other than those listed above. Other polymorphisms in the primer binding regions can affect the testing and, ultimately, the genotyping assessments made.

 

Direct DNA testing will not detect all genetic variants that alter protein function. Absence of a detectable gene mutation or polymorphism does not rule out the possibility that a patient has a genetic variant that may be impacting drug response or side effects.

 

The HTR2A gene is located on the long arm of chromosome 13 (13q). Patients identified with hematologic disorders that involve deletion of 13q should call the laboratory for instructions.

Day(s) Performed

Wednesday; 8 a.m.

Report Available

2 days

Performing Laboratory

Mayo Medical Laboratories in Rochester

Test Classification

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 U.S. Food and Drug Administration.

CPT Code Information

81479-Unlisted molecular pathology procedure

NY State Approved

Conditional