Pharmacogenetic Test: Understand How Your DNA Affects Medication Response

What is a pharmacogenetic test?

A pharmacogenetic test is a medical analysis based on DNA that determines how your genetic makeup influences the metabolism of drugs. Instead of relying solely on symptoms or prescribing based on trial and error, this test provides concrete data on how your body processes specific medications.

The science behind this test lies in pharmacogenetics, the study of how inherited gene variants influence your response to drugs. Many of these variants occur in liver enzymes, particularly those in the cytochrome P450 (CYP450) family, such as CYP2D6, CYP2C19, and CYP3A4. These enzymes are responsible for metabolizing more than 70% of commonly prescribed medications.

If you have a genetic variant that slows down or speeds up the activity of one of these enzymes, the consequences can be significant. A standard dose of a drug may become less effective, cause intolerable side effects, or even lead to drug poisoning. Without genetic testing, these reactions often remain unexplained.

When should you get tested?

A pharmacogenetic test is especially useful when there is uncertainty about how you will respond to medication. It is particularly recommended in the following cases:

• • Before starting a long-term or high-risk treatment
    For chronic conditions such as depression, anxiety, ADHD, or high blood pressure, a test can help you avoid medications that may not be effective or cause side effects based on your genetic profile.
  • If you have experienced side effects

Persistent symptoms such as nausea, dizziness, fatigue, or mood swings may be related to how your body metabolizes certain medications. Genetic mismatches can amplify these effects.

• When standard medications have not worked
  If you have tried a medication at the correct dosage without improvement, a test can explain why and help your healthcare provider find more suitable alternatives.
• If you are taking multiple medications (polypharmacy)
  A pharmacogenetic test can identify gene-drug and drug-drug interactions that increase your risk of reduced efficacy or side effects.
• If medication sensitivity runs in your family
  Pharmacogenetic traits are often inherited. If close relatives have had strong reactions to medications, you may have similar variants that influence your response.

How the test works

The pharmacogenetic test is non-invasive, easy to perform, and clinically validated. The test begins with the collection of a saliva sample, which can be taken at home or by a healthcare provider. This painless method collects epithelial cells from the inside of your mouth, which are used to extract your DNA.

Once the sample arrives at a certified laboratory, it undergoes targeted genotyping to identify specific genetic variants that influence how you metabolize medications. The analysis focuses on important genes in the CYP450 enzyme family, including CYP2D6, CYP2C19, and CYP3A4, enzymes responsible for processing a large percentage of the most commonly prescribed medications.

By evaluating whether these enzymes are fully active, partially active, or inactive, the laboratory creates a personalized pharmacogenetic profile. Based on the results, you will be classified into a category: poor, average, standard, or ultra-rapid metabolizer, depending on the gene in question.

This information helps your healthcare provider determine whether you need a different medication, an adjusted dosage, or closer monitoring to ensure safe and effective treatment.

Note: This test uses targeted gene analysis and does not sequence your entire genome.

Benefits of a pharmacogenetic test

A pharmacogenetic test supports long-term, personalized care. Here’s what you get:

• Personalized treatment based on your DNA
  Insight into how your genetic profile influences your response to medications, so your care can be tailored to your specific situation.
• Faster access to the right medication
  Reduce trial-and-error prescribing and shorten the time it takes to find an effective treatment, especially for chronic or complex conditions.
• Safer, more accurate dosing
  Prevent under- or overdosing by determining whether you are a slow, normal, or fast metabolizer of important drug-metabolizing enzymes.
• Lower risk of drug-related side effects
  Prevent common and serious reactions by choosing medications that your body can tolerate and/or process better. Some examples of these side effects are:
• Improved long-term medication planning
  Your results remain relevant throughout your life and can be used as a guide for current and future treatment decisions in various specialties, including cardiology, psychiatry, and pain management, as well as the use of oncology drugs.

Note: Your DNA remains stable throughout your life and does not change. However, your pharmacogenetic profile, based on that DNA, may be adjusted over time as scientific insights and guidelines evolve. We therefore offer you the option of receiving updates so that your profile remains in line with the most up-to-date knowledge and applications in medical practice. If desired, this profile can be shared with your healthcare providers as part of your medical file.

Recognizing side effects: which side effect goes with which medication?

Many people experience symptoms while taking medication, but do not always realize that these are side effects. Fatigue, headaches, nausea, or muscle pain can be side effects of a medication prescribed by your doctor.

Side effects vary from person to person and are partly determined by your DNA. Your genetic predisposition influences how quickly or slowly your body breaks down medications. As a result, medications may be too strong, too weak, or work incorrectly.

Below is an overview of common medications prescribed by general practitioners and typical side effects that may be associated with them:

Are you unsure whether your symptoms are caused by your medication?

Discuss this with your doctor or pharmacist. Sometimes a dose adjustment or a different medication may be possible.

A DNA medication test can help predict whether you are susceptible to certain side effects.

Tested biomarkers

The pharmacogenetic test analyzes important genes involved in the metabolism of drugs. These biomarkers help predict how your body will respond to specific medications:

• CYP2D6
  This gene plays an important role in the breakdown of many drugs, such as antidepressants (e.g., paroxetine, nortriptyline), opioids (such as codeine and tramadol), and beta blockers (e.g., metoprolol). The activity of this enzyme varies greatly from person to person: some break down drugs quickly, while others break them down slowly.
  Possible consequence: In case of slow breakdown: reduced effectiveness of drugs such as codeine (because it is not properly converted into morphine), or more side effects with antidepressants. In case of rapid breakdown: risk of excessive conversion and therefore side effects (e.g., drowsiness or breathing problems with codeine).
• CYP2C19
  Affects the effectiveness of medications such as clopidogrel (blood thinner), proton pump inhibitors, and some antidepressants. If this gene is less active, the medication may not work properly.
  Possible consequence: Less effective treatment, for example, an increased risk of thrombosis with clopidogrel.
• CYP3A4
  Processes many commonly prescribed drugs, including statins, calcium antagonists, and immunosuppressants. Although this gene itself has less genetic variation, it plays a major role in drug processing.
  Possible consequence: Small genetic differences can influence the rate of breakdown and thus the effect of drugs.
• CYP3A5
  Processes tacrolimus, a drug often used after organ transplants, among other things. Not everyone produces this enzyme: in some people, its activity is absent.
  Possible consequence: Without this enzyme, certain drugs remain in the body longer. A dosage adjustment is then necessary.
• SLCO1B1
  Influences how statins (cholesterol-lowering drugs) are absorbed in the liver. Some people have a variant that causes slower absorption.
  Possible consequence: Increased risk of muscle pain or muscle weakness when using statins, especially simvastatin. SLCO1B1 influences how statins (cholesterol-lowering drugs) are absorbed in the liver.
• TPMT and NUDT15
  These genes are both involved in the breakdown of thiopurine drugs, such as azathioprine, mercaptopurine, and thioguanine, which are used to treat autoimmune diseases and certain types of cancer. Some people have a hereditary variant that causes these drugs to be broken down much more slowly.
  Possible consequence: When using the standard dosage, this can lead to excessive exposure to the drug, with the risk of serious side effects such as bone marrow suppression (a deficiency of white blood cells, red blood cells, or platelets). A dose adjustment or alternative drug is then necessary to prevent damage.
• UGT1A1
  Helps break down bilirubin (a substance released when red blood cells break down) and drugs such as irinotecan.Some variants slow down this breakdown.
  Possible consequence: Slightly elevated bilirubin (yellow skin or eyes) or more side effects when using certain chemotherapy drugs.
• VKORC1
  Plays a central role in the functioning of blood thinners such as warfarin and acenocoumarol. Some people are more sensitive to these medications.
  Possible consequence: Lower dosage needed to prevent bleeding, especially in combination with certain CYP2C9 variants.
• CYP1A2
  This gene is involved in the breakdown of various drugs, such as theophylline, clozapine, olanzapine, and caffeine. The activity of CYP1A2 can be genetically determined to be faster or slower, and is also influenced by external factors such as smoking.
  Possible consequence: Increased activity (e.g. due to genetic predisposition or smoking) may result in too low a level of the drug, reducing its effect. Reduced activity increases the risk of side effects, such as drowsiness with antipsychotics.
• CYP2B6
  This gene is important for the breakdown of drugs such as efavirenz (HIV medication), bupropion (antidepressant), and methadone. The activity of this enzyme can vary greatly between individuals.
  Possible consequence: Slow breakdown increases the risk of side effects such as neurotoxicity with efavirenz (e.g., dizziness, sleep problems, mood disorders). Rapid breakdown can cause the drug to be excreted too quickly, making it less effective.
• CYP2C9
  This enzyme plays an important role in the breakdown of drugs such as NSAIDs (e.g., ibuprofen), phenytoin, and blood thinners such as warfarin and acenocoumarol.
  Possible consequence: With reduced activity, there is an increased risk of side effects such as bleeding (with blood thinners) or toxicity (with phenytoin). A lower dose is often needed to limit these risks.
• DPYD
  This gene codes for the enzyme dihydropyrimidine dehydrogenase, which is responsible for the breakdown of fluoropyrimidines such as 5-fluorouracil (5-FU) and capecitabine.
  Possible consequence: If activity is reduced, the drug accumulates in the body, with serious side effects such as mucositis, diarrhea, neutropenia, and in severe cases, life-threatening toxicity. The dosage must be adjusted or an alternative drug chosen.
• MTHFR
  This gene is involved in folate metabolism and may indirectly influence the effect of drugs that depend on folate, such as methotrexate.
  Possible consequence: Certain variants (e.g., C677T) may reduce the efficiency of folate metabolism. This may increase the risk of side effects from methotrexate or elevated homocysteine levels, with possible cardiovascular consequences. However, the clinical relevance of MTHFR variants in pharmacotherapy is limited and subject to debate.