Pharmacogenetics studies how your genes influence your response to medicines: how your body processes them, whether they have the expected effect and your likelihood of experiencing adverse effects.
We analyse variants in genes involved in drug metabolism, transport and sites of action. Depending on the gene, the result may describe an enzyme's metabolising capacity, a transporter's function or the presence of variants associated with specific reactions.
For drug-metabolising enzymes, the result is expressed as a metaboliser profile:
- Normal: the enzyme has the expected activity.
- Intermediate: activity is lower than usual.
- Poor: activity is very low or absent.
- Ultrarapid: activity is higher than usual.
With lower activity, a medicine may accumulate and increase adverse effects or, if it is a prodrug that the body needs to activate, such as codeine or clopidogrel, be less effective. With higher activity, the opposite can occur: the medicine may be less effective or, if it is a prodrug, be activated excessively and increase adverse effects.
For transporters, the result indicates whether function is normal, reduced or low; for other genes, it shows whether you have variants associated with an increased risk of certain reactions, such as hypersensitivity.
This is guidance that your doctor can consider alongside your medical history. Never change or stop treatment on your own.