A Complete Guide to Pharmacogenetics
What is pharmacogenetics?
Pharmacogenetics (PGx) brings together two fields of science, pharmacology and genetics, to help healthcare providers individualize care for their patients.
Pharmacogenetics is often used interchangeably with pharmacogenomics, but these terms actually have slight differences in meaning. What’s the difference between pharmacogenetics and pharmacogenomics?
Simply put, pharmacogenomics is the study of how all genes (the genome) can affect responses to drugs.
When referring to how an individual gene variant can impact a response to a single drug, scientists use the term pharmacogenetics.
What is the purpose of pharmacogenetics?
The purpose of pharmacogenetics is to help provide genetic guidance for three important aspects of prescribing: drug efficacy, dosage, and prevention of side effects.
- Efficacy: Which medications may be more effective.
- Side Effects: Which medications may have unpleasant or dangerous effects.
- Dosage: What dosing may be appropriate based on how your body metabolizes medication.
How does genetics affect drug response?
One of the main functions of genes is to provide your cells with instructions for making proteins.
Proteins are molecules responsible for many bodily functions, for example, the structure of cells, and the regulation of tissues and organs.
One important example is how certain proteins are responsible for the metabolism (breaking down) of many commonly-used drugs.
Because there are different versions of genes, the instructions for proteins vary, and the way your body interacts with a drug may also vary as a result. These genetic variations are important for healthcare providers to consider when making prescribing decisions.
There are two primary mechanisms used to understand the way genetics can impact an individual’s response to medications: pharmacokinetic effects and pharmacodynamic effects.
Pharmacodynamics can be described as what a drug does to the body, or the study of biochemical, physiologic, and molecular effects of a drug on the body.4
Here’s how it works:
When a drug enters your body, it usually starts interacting with cell receptors, which creates a signal that leads to a biological response.
This part can get a little complicated, but here’s the short version:
Variations in genes can lead to variations in cell receptors or other drug targets, and that can lead to variations in biological drug response.
Pharmacodynamics can help predict the effect a particular drug may have on an individual and may help inform drug choice.
How does pharmacogenetic testing work?
- Pharmacogenetic testing is typically administered with a simple cheek swab to collect a buccal sample, much like commercial DNA tests.
- The sample is evaluated by a certified laboratory technician, who looks for specific gene variants associated with altered drug metabolism or differential therapeutic effects (like adverse side effects).
- The laboratory technician reports the results electronically to the licensed healthcare provider to be used in prescribing guidance.
Because pharmacogenetic testing provides guidance for prescription medications, PGx testing (in the United States) requires a prescription from a licensed healthcare provider.
How accurate is pharmacogenetic testing?
Trusted Pharmacogenetic Sources
FDA Labels and Pharmacogenetic Associations
Clinical Pharmacogenomics Implementation Consortium (CPIC)
CPIC plays a key role in standardizing pharmacogenetics and produces peer reviewed PGx guidelines. You can view their full Genes-Drugs table online.
PharmGKB’s Extensive Database
Royal Dutch Pharmacists Association (KNMP)
KNMP is the Dutch pharmacist trade organization that founded DPWG (Dutch PGx Working Group). DPWG is a consortium of researchers in Europe who work together to translate PGx research into clinical guidelines.
Should genetics be considered before giving a person a drug?
Personalized medicine is becoming increasingly common and more routine in today’s world. For decades, certain pieces of the puzzle have been considered when making prescribing decisions, like family history, environmental factors (such as smoking), lifestyle, and other medications an individual may be taking.
Genetics represents a missing piece of the puzzle that is now accessible through pharmacogenetic testing. PGx tests are designed to help reduce trial and error prescribing and assist healthcare providers in making safer medication choices.
At Genomind, we are committed to providing the most advanced and comprehensive pharmacogenetic testing for mental health. We believe genetics is a crucial factor to consider before prescribing a medication.
If you would like to learn more about our test and services, visit our Genomind Pharmacogenetic Testing page.
- Carson, P. E., Flanagan, C. L., Ickes, C. E., & Alving, A. S. (1956). Enzymatic Deficiency in Primaquine-Sensitive Erythrocytes. Science, 124(3220), 484–485. https://doi.org/10.1126/science.124.3220.484-a
- MedlinePlus. (2020, September 9). Glucose-6-phosphate dehydrogenase deficiency: MedlinePlus Genetics. https://medlineplus.gov/genetics/condition/glucose-6-phosphate-dehydrogenase-deficiency/
- Merck Manuals. (2020, October). Overview of Pharmacokinetics. Merck Manuals Professional Edition. https://www.merckmanuals.com/professional/clinical-pharmacology/pharmacokinetics/overview-of-pharmacokinetics
- Merck Manuals. (2019, June). Overview of Pharmacodynamics. Merck Manuals Professional Edition. https://www.merckmanuals.com/professional/clinical-pharmacology/pharmacodynamics/overview-of-pharmacodynamics
- Burns, P. B., Rohrich, R. J., & Chung, K. C. (2011). The Levels of Evidence and Their Role in Evidence-Based Medicine. Plastic and Reconstructive Surgery, 128(1), 305–310. https://doi.org/10.1097/prs.0b013e318219c171
- Center for Devices and Radiological Health. (2020, March 18). Table of Pharmacogenetic Associations. U.S. Food and Drug Administration. https://www.fda.gov/medical-devices/precision-medicine/table-pharmacogenetic-associations#about