Serotonin Transporter (5-HTTLPR) Genotyping
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Test Code
5-HTT
CPT Codes
83898 x1 ; 83894 x1 ; 83912 x1 ; 83912-25 x1
Specimen
Whole blood or buccal swabs
Volume
5 mL of whole blood or four buccal swabs
Minimum Volume
3 mL of whole blood or four buccal swabs
Container
Lavender-stopper (EDTA) tube or paper envelope for dried buccal swabs
Storage Instructions
Maintain at room temperature or refrigerate
Cause for Rejection
Hemolyzed specimen; quantity not sufficient
Use
The serotonin transporter removes serotonin from the synapse of serotonergic neurons, resulting in serotonin reuptake into the presynaptic terminus. Elevated synaptic serotonin levels are associated with improved mood; thus the effectiveness of many antidepressant drugs (namely selective serotonin reuptake inhibitors, SSRIs) is thought to be due to their inhibition of the serotonin transporter, ultimately increasing serotonin availability in the synaptic cleft. The 5-HTTLPR gene polymorphism is a 44-bp insertion/deletion in the serotonin transporter gene, 5-HTT or SLC6A4. The two most frequent alleles are defined by their lengths and are referred to as Long (L) and Short (S). The S allele results in less expression of the active transporter and is associated with delayed response to antidepressants and increased risk of adverse drug reactions (ADRs) during antidepressant therapy.
Limitations
Other variants of the 5-HTT gene that are not detected in this assay may influence drug response.
Methodology
Polymerase chain reaction combined with agarose gel analysis.
Turnaround Time
Five business days after receipt of specimen. STAT turnaround time of 3 business days is available for an additional charge.
