Does Pillcheck report pharmacodynamic genes for mental health medications?

Not currently. Pillcheck reports genes that published clinical guidelines support for choosing or dosing mental health medications. Currently, this includes pharmacokinetic genes with strong, guideline-supported evidence. Pharmacodynamic genes don’t yet meet that standard.

Two types of genes in pharmacogenetic testing

1. Pharmacokinetic genes affect how your body absorbs, breaks down and clears a medication, which changes how much of the drug is in your blood. Examples are CYP2D6, CYP2C19 and CYP2B6.
2. Pharmacodynamic genes affect the receptors and other proteins a medication acts on, which may change how your body responds to the drug. Examples are the serotonin transporter gene (SLC6A4) and the serotonin-2A receptor gene (HTR2A).

Put simply, pharmacokinetic genes affect how much of a medication reaches its target, and pharmacodynamic genes affect how the target responds.

Pharmacodynamic genes people often ask about

• SLC6A4 and HTR2A: CPIC’s 2023 antidepressant guideline reviewed both and made no recommendation, citing mixed and insufficient evidence (Bousman et al., 2023).
• COMT: Sometimes discussed for stimulant medications such as Adderall or Ritalin. It isn’t supported by clinical pharmacogenetic guidelines.
• MTHFR: Sometimes suggested for depression treatment and folate metabolism. It isn’t supported by clinical pharmacogenetic guidelines.
• DRD2: Studied for antipsychotic response, but it falls below the evidence threshold set by guideline bodies, and neither the FDA nor the European Medicines Agency (EMA) requires testing for it (Baldacci et al., 2023).

Why some testing providers report pharmacodynamic genes

Some pharmacogenetic tests include pharmacodynamic genes because research suggests these genes may play a role in treatment response, and a larger gene panel can seem more complete. Providers also combine genes in different ways, often using their own algorithms. As a result, different tests can give different recommendations for the same person, which can leave patients and prescribers unsure which result to follow.

Why Pillcheck doesn’t report them for psychiatric medications

• Inconsistent evidence. Large, well-controlled studies haven’t shown that these genes reliably predict how a person will respond to a specific psychiatric medication.
• No guideline or regulatory support. No Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline or FDA drug label recommends testing these genes to choose a psychiatric medication or dose.
• Many factors affect treatment response. Dose, other medications, lifestyle and the condition itself all play a role. Each pharmacodynamic gene explains only a small part of the difference between people.
• Expert caution. A task force of the American Psychiatric Association concluded there wasn’t enough evidence to support the widespread use of combinatorial (pharmacokinetic and pharmacodynamic) test results to guide antidepressant prescribing.

What Pillcheck reports instead

For psychiatric medications, Pillcheck reports pharmacokinetic genes with strong, guideline-supported evidence, such as CYP2D6, CYP2C19 and CYP2B6. These guide dosing and medication choice for many antidepressants, antipsychotics and ADHD medications. The 2026 consensus guidelines from the German Association for Neuropsychopharmacology and Pharmacopsychiatry (AGNP) also limit actionable guidance to genes like these (Hart et al., 2026).

Will this change?

Pillcheck follows published pharmacogenetic guidelines. If guidelines are established for pharmacodynamic genes, we’ll add them to the Pillcheck report.

Related

• What genes does Pillcheck test?
• How accurate is the Pillcheck test?
• Genetic testing for psychiatric medications (blog)