NHS pharmacogenomic test improved for patients of African ancestry

A routine genetic test used by the NHS to guide prescription of a common chemotherapeutic drug now includes a genetic variant more prevalent in people of African descent.

The Manchester University NHS Foundation Trust's North West Genomic Laboratory Hub (GLH) first started using the extended test in September 2025. So far, it has identified three people at higher risk of adverse effects from fluoropyrimidine-based chemotherapy, who then received an adjusted prescription.

Dr Vivek Misra, consultant clinical oncologist at the Christie NHS Trust Hospital in Manchester, said: 'It is really great that the North West GLH was able to pick up this mutation. I have started the patient's treatment with a dose reduction which I otherwise would not have done and she could have experienced more toxicity by being on the full dose of capecitabine.'

Fluoropyrimidines are a type of drug commonly used to treat solid tumours in breast, colorectal, gastric and other cancers. Due to their genetic background, however, certain people are at a higher risk of experiencing severe adverse effects to the medication, which in some cases can be fatal. As part of increasing efforts for pre-emptive pharmacogenomic testing (see BioNews 1139 and 1178), patients in the UK undergo a genetic test to assess their risk before receiving this treatment.

The test screens for genetic variants that result in a deficiency in dihydropyrimidine dehydrogenase (DPD) – the enzyme that breaks down fluoropyrimidines. Without a properly functioning DPP enzyme, a patient cannot adequately clear the drug from their body, leading to increased toxicity.

Before 2025, the test only checked for four genetic variants of DPYD (the gene that encodes the enzyme), all of which are common in individuals of white European ancestry. Patients from other ethnic backgrounds, who are more likely to carry different DPYD variants linked to fluoropyrimidine toxicity, were therefore at higher risk of being missed during screening. The extended test, which will now be offered by the NHS across England, includes a fifth variant, c.557A>G, found in around two percent of people of African ancestry.

This change follows recommendations issued in a systematic review by the NHS Race and Health Observatory in partnership with the University of Liverpool, which was published in the British Journal of Cancer.

Academic general practitioner Dr Veline L'Esperance, who serves as senior clinical advisor to the NHS Race and Health Observatory, noted that 'this moment represents something rare in healthcare, research translated into policy, and policy translated into practice, with tangible results for patients who have historically been left behind.'

She added: 'Including this variant is not simply a technical update; it is proof that when we commit to equity at every stage of the pipeline, from the evidence base through to clinical implementation, we can close gaps that should never have existed. Patients of African ancestry deserve the same standard of safety as everyone else, and now clinicians have the means to deliver it.'