How Pharmacogenetic Testing is Revolutionising Adverse Drug Reaction Prevention

Are you tired of experiencing unpleasant side effects from medications? You’re not alone. Adverse drug reactions (ADR) affect up to 40% of patients undergoing pharmacological treatment, accounting for 15% of hospital spending in OECD countries [1]. But did you know that your genes could be the culprit behind these reactions?

Genetic factors play a crucial role in drug metabolism and can significantly impact how your body responds to medication. Variations in protein-coding genes can affect drug pharmacokinetics, making some people more susceptible to ADR than others. For example, if you carry a variation in the DPYD gene, you may be at risk for induced toxicity from fluoropyrimidine treatment, a chemotherapy drug used to treat colorectal, breast, and gastric cancers. This can result in severe treatment-related toxicity, including diarrhea, mucositis, and myelosuppression, and even a 1% chance of mortality.

Thankfully, recent advancements in genetic sequencing have allowed hospitals to adopt genotype-guided prescribing strategies to prevent severe ADR. By identifying variations in genes like DPYD, clinicians can customize treatment dosage to reduce the risk of ADR and improve patient outcomes. This effective approach of customizing drug therapy through pharmacogenetic testing is not limited to fluoropyrimidine treatment alone. It has been successfully demonstrated in various drug-gene combinations, including abacavir, warfarin, thiopurine, and P2Y12 inhibitors [2,3].

A recent study involving almost 7,000 patients with various diseases evaluated the usefulness of pre-emptive testing for a panel of genetic variants associated with 39 drugs. Half of the participants were tested for 50 known variants in 12 genes, and if a variant associated with an adverse reaction was identified, their treatment plan was modified accordingly. The remaining half of the group did not undergo any genetic testing and continued with the prescribed drugs. Interestingly, the study revealed a 30 percent reduction in the frequency of adverse reactions among the tested group. This approach is more efficient than testing a patient for a single gene when prescribing a specific drug [4].

Pharmacogenetic testing has proven to be effective in customizing drug therapy and reducing the risk of ADR. By identifying genetic variations in patients, clinicians can personalize treatment plans and ensure that patients receive the right drug at the right dose. As genetic sequencing technology continues to advance, it is likely that pharmacogenetic testing will become more widespread and play an increasingly important role in clinical practice. So, don’t suffer in silence – talk to your doctor about pharmacogenetic testing and how it can help you avoid adverse drug reactions.


  1. Slawomirski, L., A. Auraaen, and N.S. Klazinga, The economics of patient safety: strengthening a value-based approach to reducing patient harm at national level. 2017.
  2. Henricks, L.M., et al., DPYD genotype-guided dose individualisation of fluoropyrimidine therapy in patients with cancer: a prospective safety analysis. The Lancet Oncology, 2018. 19(11): p. 1459-1467.
  3. Knikman, J.E., et al., Individualized dosing of fluoropyrimidine‐based chemotherapy to prevent severe fluoropyrimidine‐related toxicity: what are the options? Clinical Pharmacology & Therapeutics, 2021. 109(3): p. 591-604.
  4. Swen, J.J., et al., A 12-gene pharmacogenetic panel to prevent adverse drug reactions: an open-label, multicentre, controlled, cluster-randomised crossover implementation study. The Lancet, 2023. 401(10374): p. 347-356.

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