Pharmacogenomics in Healthcare: Using Genetics to Personalize Drug Prescriptions in the NHS

Pharmacogenomics uses genetic information to predict how medicines will affect an individual. The Conversation explains that many people carry variants that influence drug efficacy and safety, how NHS testing is already being used for select drugs, and what a broader rollout could mean for personalized prescribing, safety, and costs. It also emphasizes that genes are only part of the picture and that robust evidence and clinician training are essential for routine implementation. Original publication by The Conversation.

• Genetic testing can reduce adverse drug reactions when there is strong evidence linking gene variants to drug outcomes.
• DPYD testing before certain chemotherapy and HLA-B testing before abacavir are among five drug-gene pairs currently used in England.
• National studies funded by NHS England are exploring a phase II rollout and how results can be integrated into clinical computer systems.
• Results could be stored in medical records for lifetime use, aiding prescribing decisions across a patient’s life.

Introduction to pharmacogenomics

Pharmacogenomics is the field that uses genetic information to predict how a person will respond to medicines. Some genes code for enzymes that metabolize drugs, others influence how drugs act at their targets. Variants in these genes can alter treatment effectiveness or side effect risk. The article also notes that non-genetic factors such as age, kidney and liver function, other medicines, and the condition being treated all influence response. Importantly, almost everyone carries a relevant variant, but the immediate clinical value depends on whether a patient will be prescribed or currently taking a medicine where guidance exists on how to adjust care.

Scale of genetic variation and its potential impact

Research analyzing nearly 500,000 UK Biobank participants found that 99.5% were predicted to have an unusual drug response due to variants in 14 well-studied genes. Nearly one-quarter had already been prescribed a medicine affected by one of those genes. While this figure underscores genetic diversity, its practical significance hinges on whether there is strong evidence to change prescribing in real-world settings.

Evidence base and economic considerations

The value of genetic testing in improving safety and outcomes has been demonstrated in trials. A 2022 study at a Liverpool NHS trust estimated that adverse drug reactions contributed to 16.5% of admissions within a month of medical care. While this is a single-trust estimate, it highlights the potential cost of avoidable harm to the NHS. A European trial involving 6,944 patients across seven countries showed that when care was guided by pharmacogenomic results, clinically relevant adverse reactions within 12 weeks occurred in 21% of patients compared to 27.7% with standard care. These findings point to potential improvements in patient outcomes and hospital resource use, but broader adoption requires robust testing infrastructure and guidance updates.

Current testing and implementation in England and the Netherlands

England’s NHS provides guidelines for testing in five drug-gene pairs, including DPYD testing before certain chemotherapy drugs and HLA-B testing before abacavir. A national NHS England study is examining how a phased rollout could work, including how results and prescribing advice could be integrated into clinical computer systems. In the Netherlands, pharmacogenetic guidance is incorporated into the national medicines database, enabling point-of-care guidance when a patient’s results are known, though access to testing remains a separate issue.

How could a genetic test change treatment?

Genetic results could support choosing a drug or adjusting dose in conditions such as after a heart attack, where clopidogrel, statins, and proton pump inhibitors might be used. Variants in CYP2C19 can reduce clopidogrel activation, while other gene variants influence statin tolerance and proton pump inhibitor effectiveness. Antidepressants can also be affected by CYP2D6 and CYP2C19 variants. The overall message is that pharmacogenomic data add to, but do not replace, clinical assessment and decision-making.

Practical considerations and future directions

A genetic test typically uses a cheek swab or blood sample, and results can be stored in a patient’s medical record for life. However, interpretations may evolve as evidence and guidelines update. Wider use will require reliable testing, current guidance, integration into health records and systems, and clinician training. Equity considerations are essential to ensure those most likely to benefit have access to testing as part of routine care.

Who could benefit?

People on several medicines have more opportunities to encounter a relevant drug-gene combination. The NHS already has some infrastructure in place, but broader access will require careful planning to ensure testing reaches those who need it most. Pharmacogenomics can reduce some trial-and-error in prescribing when a gene-drug relationship is well evidenced, but it is only part of the bigger picture of personalized medicine.

Conclusion

The practical question for clinicians and patients is how to make pharmacogenomic testing a routine part of prescribing, supported by reliable evidence, up-to-date guidance, and trained healthcare professionals. The article highlights that progress is underway but careful planning and ongoing evaluation are essential to maximise safety, effectiveness, and equity in drug treatment.