Genomic medicine and pharmacogenomics
Using a person's genome to choose drugs and doses, screen populations and diagnose sick newborns quickly.
Key facts
- Pharmacogenomics studies how inherited variants change drug response; expert groups (such as CPIC) publish gene–drug guidelines.
- HLA-B*57:01 predicts hypersensitivity to abacavir, so it is tested before treatment; HLA-B*15:02, frequent in South-East Asian ancestry, predicts severe skin reactions to carbamazepine.
- CYP2C19 poor metabolisers activate clopidogrel poorly; CYP2D6 ultrarapid metabolisers turn codeine into too much morphine, which has caused deaths in children.
- TPMT and NUDT15 variants make thiopurines (azathioprine, mercaptopurine) toxic to the marrow; DPYD variants make fluorouracil and capecitabine toxic; CYP2C9 and VKORC1 affect warfarin needs.
- Population genetic screening: newborn screening for treatable disorders and cascade testing of relatives once a family variant is known.
In detail
- Drug response is usually a complex trait: several genes plus age, organ function, interactions and adherence all play a part.
- Rapid genome sequencing in critically ill newborns can give a diagnosis within days and change treatment.
- Tumour sequencing chooses targeted cancer drugs; germline findings in the tumour report may reveal hereditary cancer.
- G6PD deficiency is a gene–drug interaction too: oxidant drugs such as primaquine and rasburicase cause haemolysis.
- Polygenic risk scores may later refine screening, but are not yet standard care.
- Also called
- Precision medicine, Gene–drug pairs
Clinical notes
- Ask about previous drug reactions in relatives; a family history of anaesthetic death suggests malignant hyperthermia susceptibility (RYR1).
- Pharmacogenetic results last a lifetime and should be recorded where every prescriber can see them.
Test yourself
Think of the answer, then tap the question to see it.
Which test is done before starting abacavir?
HLA-B*57:01; carriers have a high risk of hypersensitivity and should not receive the drug.
Why is codeine dangerous in CYP2D6 ultrarapid metabolisers?
They convert codeine to morphine quickly, which can cause life-threatening opioid toxicity.
Which gene variants predict severe thiopurine toxicity?
TPMT and NUDT15.
Connections
Educational information, not medical advice. For any symptom, see a health professional.
Sources: What is pharmacogenomics?: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026); Pharmacogenomics (National Human Genome Research Institute (NHGRI), 2026); What is precision medicine?: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026); ClinPGx (CPIC guidelines) (Clinical Pharmacogenetics Implementation Consortium (CPIC) and PharmGKB, 2026).
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Representative model, for educational purposes only.