Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

HTR2O
60338
pharmacogenetic findings in major depressive disorder. Molecular Psychiatry 2010;15:473-500 2.
Arranz MJ, Murno J, Birkett J, et al: Pharmacogenetic prediction of clozapine response. Lancet
2000;355(9215):1615-1616 3. Davies MA, Setola V, Strachan RT, et al: Pharmacologic analysis of
non-synonymous coding h5-HT(2A) SNPs reveals alterations in atypical antipsychotic and agonist
efficacies. Pharmacogenomics Journal, 2006;6:42-51 4. McMahon FJ, Buervenich S, Charney D, et al:
Variation in the gene encoding the serotonin 2A receptor is associated with outcome of antidepressant
treatment. Am J Hum Genet 2006;78:804-814 5. Masellis M, Basile V, Meltzer HY, et al: Serotonin
subtype 2 receptor genes and clinical response to clozapine in schizophrenia patients.
Neuropsychopharmacology, 1998;19:123-132 6. Reynolds GP, Zhang ZJ, Zhang XB: Polymorphism of
the promoter region of the serotonin 5-HT2C receptor gene and clozapine-induced weight gain. Am J
Psychiatry 2003;160:677-679 7. Templeman LA, Reynolds GP, Arranz B, San L: Polymorphisms of the
5-HT2C receptor and leptin genes are associated with antipsychotic drug-induced weight gain in
Caucasian subjects with a first-episode psychosis. Pharmacogenetics and Genomics,
2005;15(4):195-200
Serotonin Receptor Genotype (HTR2A and HTR2C), Saliva
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) resulting in increased drug levels and increased risk for adverse drug reactions.(2)
Patients with polymorphic variants in the HTR2A/2C serotonin receptors may be considered for switching
to non-SSRI antidepressants that block the type 2 receptors. Allelic variations in the HTR2A and HTR2C
genes have been linked with response to the antipsychotic drug clozapine. The presence of the HTR2A
receptor allele His452 has been reported to predict favorable response to clozapine therapy.(3) -Treatment
with atypical 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) -Allelic
variation in the HTR2A and HTR2C genes has also been associated with increased risk of tardive
dyskinesia in schizophrenic patients.(5,6) -Allelic variation in the HTR2A gene and its promoter have
been associated with improved effectiveness of citalopram in major depression disorder. Allele
nomenclature Gene Nucleotide Change Amino Acid Change HTR2A 1438G->A Promoter polymorphism
HTR2A 74C->A Thr25Asp HTR2A IVS2+54538 A->G Non-coding HTR2A 1354C->T His452Tyr
HTR2C -759C->T Promoter polymorphism
Useful For: Guiding treatment choice of an (selective serotonin reuptake inhibitor) SSRI or non-SSRI
antidepressant. Individuals homozygous for the IVS2+54538 A allele have improved probability of
response to citalopram, in contrast to individuals homozygous or heterozygous for the IVS2 G allele.
Individuals with major depression disorders are more likely to respond to citalopram if they are
homozygous for the -1438G promoter allele. 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 Identifying those patients receiving atypical
antipsychotic medications with excessive weight gain who may benefit by switching to different
antipsychotic medications
Interpretation: An interpretive report will be provided.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Malhotra AK, Murphy GM Jr, Kennedy JL: Pharmacogenetics of
psychotropic drug response. Am J Psychiatry 2004;161(5):780-796 2. Murphy GM Jr, Kremer C,
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