The UKCPA Genomics community was formed in 2022 to bring together pharmacy professionals with an interest in the rapidly-developing field of genomic medicine. Since the publication of the first human genome (full DNA sequence) in the early 2000’s, genomic testing has become ever faster and cheaper, and it is now widely used in the NHS for diagnosis of cancer and rare disease.
Pharmacogenomics, where a DNA sequence is used to predict the response to, and metabolism of, medicines, and the risk of adverse effects from medicines, is starting to become more commonplace within the NHS and is offered by some private providers.
In this article, we provide an overview of what we consider to be the key core concepts of genomics for pharmacy teams, as genomic literacy is going to be important for us to help patients get the most from their medicines using this new technology.
Understanding the fundamentals of genomics
DNA makes RNA makes protein. Four ‘letters’ make up the genomic code of DNA: A, T, C, G
The human genome has three billion letters. A single letter change in the DNA sequence, as well as larger changes, can cause disease but there is lots of normal human variation too (such as those responsible for eye colour)
Genes are sequences of DNA that code for proteins. However, these only make up around two percent of the genome; the remainder is involved in the regulation of gene expression and other cellular processes, and studying sequences outside of genes is sometimes useful in understanding pathology. The terms genetics and genomics are therefore not identical but are often used interchangeably.
Applications of genomics in healthcare: diagnosis and treatment
Genomic medicine allows us to diagnose and categorise diseases (such as monogenic diabetes, which doesn’t require insulin therapy), trace inherited genetic conditions through families (e.g. familial hypercholesterolaemia), and categorise cancers according to prognostic indicators. It can also be used to identify pathogens and predict antimicrobial susceptibility, and track outbreaks and evolution of pathogen (e.g. Coronavirus).
Genomic medicine includes gene therapy, where we can replace missing genes to treat disease (e.g. zolgensma in spinal muscular atrophy), and CAR-T where white blood cells are taken from patients with cancer and programmed to target cancerous cells before being returned to the patient. Some medicines have gene-sequence based targets (e.g. ivacaftor/lumacaftor in CF, cancer therapies targeted to specific pathways such as tyrosine kinase inhibitors, NTRK inhibitors).
Genomic medicine also includes pharmacogenomics which uses sequencing to predict drug metabolism and risk of adverse effects, and for example whether a drug target is present.
How pharmacogenomics can be used to predict drug metabolism, action and adverse effects
There are hundreds of drug-gene pairs where we can predict whether someone is likely to be a low- , high- or normal-metaboliser, or even non-metaboliser, for a medicine. This information can be used to modify:
Dose, if low metabolism would result in toxicity (e.g. patients with DPYD low-metaboliser variants being prescribed fluoropyrimidines)
Drug choice, if low metabolism would result in inactivity (e.g. prodrug clopidogrel not activated sufficiently by CYP2C19, resulting in lack of antiplatelet effect).
Adverse events can be predicted by HLA typing for some medicines, e.g. allopurinol, abacavir, carbamazepine. The DNA sequences that are associated with these ADRs vary according to ancestry of patients.
More evidence is needed, particularly in real-world situations, and not all pharmacogenomic tests are currently commissioned in the UK. Pharmacy teams should contribute to this research effort.
Genomics is just part of the puzzle
A patient-centred approach to medicines uses pharmacogenomics alongside renal and hepatic function, cost-effectiveness, drug interactions and other patient factors to decide on the right medicine for the patient, at the right dose, at the right time.
Pharmacy teams should be ready to have conversations about genomics with patients, the public, and the multidisciplinary team.
Increasing use of direct-to-consumer tests, and awareness of genomics, will bring patients to discuss these issues with you. Pharmacy teams across the healthcare system need to be ready to explain benefits and limitations, and signpost to patient information.
If you would like to know more, please join the UKCPA Genomics community where you can access the online forum and educational opportunities in genomics, plus recordings of webinars and other resources.
Further reading
- Pharmacy’s guide to genomic medicine (overview of educational and reference resources)
- Why primary care is the ideal setting for using pharmacogenetic testing
- Free educational resources are available via the NHS England Genomics Education, including bitesize educational resources, blogs and webinars, and longer courses. This will soon include a pharmacy-specific resources page.
- The GeNotes resource is designed as a ‘just in time’ clinical resource to support clinicians who see patients with a genetic diagnosis, but also includes a section on pharmacogenomics.
- CPPE have a genomics homepage with learning packages including the recently-launched ‘Genomics in pharmacy: an introduction to person-centred consultations (2024)’ (free to access for NHS staff).
- The NHS-England funded national Medicines Learning Portal hosted by University Hospital Southampton has a dedicated section on pharmacogenomics for pharmacy staff with case studies to work through (free access to all, including outside of the UK).
The opinions expressed in this article are those of the author. They do not purport to reflect the opinions or views of the UKCPA or its members. We encourage readers to follow links and references to primary research papers and guidance.
Competing interest statement:
The author declares: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
