HTR2A Genotyping

HTR2A is a post-synaptic serotonin receptor that binds serotonin and is involved in amplification of excitatory signals to other neurons in the brain. HTR2A is located in many regions of the brain. The involvement of HTR2A in antidepressant and antipsychotic effectiveness and risk of side effects is not fully understood, however, blocking the HTR2A receptor may improve antidepressant effectiveness.[52] Some polymorphisms of this gene may decrease receptor density and activity in some areas of the brain, which may affect antidepressant and antipsychotic response and risk of adverse effects. Genetic variants tested for HTR2A are c.-998G>A (c.-1438G>A), c.614-2211T>C (c.1178G>A).

Indication for HTR2A Testing

Individuals initiating an antidepressant or antipsychotic or with a history of adverse drug effects or reactions to SSRIs (Selective Serotonin Reuptake Inhibitors) may be good candidates for HTR2A testing. Testing for HTR2A polymorphisms may help predict which patients may be more likely to experience SSRI-induced adverse effects and provide supplemental information to determine if patients will adequately respond to therapy.[53] Decisions to modify therapy should not be based solely on HTR2A polymorphisms as multiple factors in addition to the HTR2A polymorphism likely contribute to antidepressant and antipsychotic response.