Sorted By Test Name - Mayo Medical Laboratories

FPORC
91763
HTT
83302
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,
Rodrigues HE, et al: Pharmacogenetics of antidepressants medication intolerance. Am J Psychiatry
2003;160(10):1830-1835 3. Arranz MJ, Murno J, Birkett J, et al: Pharmacogenetic prediction of clozapine
response. Lancet 2000;355(9215):1615-1616 4. 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 5. Segman RH, Heresco-Levy U, Finkel B, et al: Association between the
serotonin 2A receptor gene and tardive dyskinesia in chronic schizophrenia. Mol Psychiatry
2001;6(2):225-229 6. Segman RH, Heresco-Levy U, Finkel B, et al: Association between the serotonin
2C receptor gene and tardive dyskinesia in chronic schizophrenia: additive contribution of 5-HT2Cser and
DRD3gly alleles to susceptibility. Psychopharmacology 2000;152(4):408-413 7. Choi MJ, Kang RH,
Ham BJ, et al: Serotonin receptor 2A gene polymorphism (-1438A->G) and short-term treatment response
to citalopram. Neuropsychobiology 2005;52:155-162 8. 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
Serotonin Release Assay, Unfractionated Heparin
Reference Values:
An interpretive comment included with results.
Test Performed by: BloodCenter of Wisconsin
638 N. 18th Street
Milwaukee, WI 53233-2121
Serotonin Transporter Genotype, Blood
Clinical Information: Serotonin (5-hydroxytryptamine; 5-HT) is a neurotransmitter. The serotonin
transporter (5-HTT) modulates neurotransmission by facilitating removal of serotonin from the synapse of
serotonergic neurons, resulting in serotonin reuptake into the presynaptic terminus. Other designations for
5-HTT are SLC6A4 (solute carrier family 6 [neurotransmitter transporter, serotonin], member 4), hSERT,
OCD1, SERT, sodium-dependent serotonin transporter, and 5-HT transporter. Selective serotonin
reuptake inhibitors (SSRIs) block the action of the serotonin transporter and are used to treat depression
and other neuropsychiatric disorders. Examples of SSRIs are fluoxetine (Prozac), fluvoxamine (Luvox),
escitalopram oxalate (Lexapro), sertraline (Zoloft), citalopram (Celexa), and paroxetine (Paxil, Paxil CR).
The 5-HTT gene is located at 17q11.1-q12 and is composed of 14 exons spanning 31 kb. A 44-base pair
promoter insertion/deletion polymorphism called LPR, or linked polymorphic region, produces alleles
described as long or short. The short allele is dominant and results in decreased concentration of the
transporter protein and a poorer response to stressful events. While individuals homozygous for the long
allele (l/l) may demonstrate response to SSRI therapy in 3 to 4 weeks, individuals with the short allele (l/s
or s/s) may respond to SSRI therapy more slowly, taking up to 12 weeks.
Useful For: Evaluating patients who have failed therapy with selective serotonin reuptake inhibitors
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