What is Pharmacogenomics?
PGx is the study of genetic variations that influence medication response. PGx is now enabling doctors to test for specific genetic changes to predict whether a patient may have a normal response, a poor response, or a higher risk of side effects before prescribing a specific medication.
WHAT IS A MYDNA MEDICATION TEST?
The myDNA Medication tests use pharmacogenomics to identify variations in a number of genes that influence medication response.
Currently, myDNA Medication reports concentrate on the genes encoding the metabolising enzymes (i.e. CYP450 enzymes) which are found mainly in the liver as well as the gut wall. These genetic variations predict the level of enzyme activity which in turn results in increased or decreased plasma concentrations and drug exposure.
Increased plasma concentrations, due to reduced enzyme activity, can lead to adverse effects. Reduced plasma concentrations, due to increased enzyme activity, can lead to poor therapeutic response.
myDNA offers a multiple gene medication test, which covers multiple medication categories (currently in excess of 80 medications). If information on medications in a specific therapeutic area is of interest, myDNA offers four single category medication reports as shown below.
- Pain medication
- Mental health medications
- Cardiovascular medications
- Gastrointestinal medications.
Enzyme function can also be affected by factors other than genotype, including age, the effect of co-administered drugs (i.e. drug-drug interactions), and the presence of liver disease. These should be taken into account when considering the myDNA Medication Reports.
Reports must be delivered by a suitable healthcare professional. Ventures has worked with myDNA to provide tailored training for New Zealand clinical staff to assist in the understanding and delivery of these reports. If you would like to know more about this training, please email us: firstname.lastname@example.org.
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WHICH PATIENTS BENEFIT FROM PGx TESTING?
All patients may benefit from PGx testing, however some patients are more likely to see an immediate benefit from PGx testing, including those:
- Experiencing side effects to specific medications;
- Not responding to specific medications;
- Requiring doses of specific medicationsoutside the recommended range; and
- Taking multiple medications.
Medication covered by the myDNA medication test
The myDNA Medication test examines the important DNA variants that affect drug response for over 80 medications used in clinical practice. These include certain antidepressants, antipsychotics, analgesics, anticoagulants, antiplatelets and proton pump inhibitors. Current TGA regulations prohibit the myDNA website from listing individual medications by name, but a list of the main medications that can be tested for is available for doctors and pharmacists. Please email us: email@example.com to request a copy of the myDNA Quick Reference Medication list.
EVIDENCE BEHIND PHARMACOGENOMIC TESTING
In our reports, myDNA references the guidelines of the Royal Dutch Pharmacists Association – Pharmacogenetics Pharmacogenomics Working Group and the Clinical Pharmacogenetics Implementation Consortium (CPIC). Generally, the emphasis is on CPIC guidelines, given their more recent publication.
The following published guidelines contain evidence for gene-drug associations for which dosage adjustments have been recommended. These can be accessed online at CPIC.
- CPIC Guideline for CYP2D6 and CYP2C19 genotypes and dosing of Tricyclic Antidepressants
- CPIC Guideline for CYP2D6 and CYP2C19 genotypes and dosing of Selective Serotonin Reuptake Inhibitors (SSRIs)
- Dutch Pharmacogenetics Working Group guidelines which include a number of antidepressant and antipsychotic medications