Providing the right patient with the right dose of the right medicine is the aim of personalised medicine. Variation in an individual’s genetic makeup compared to others in the general population can affect their response to medications because some of these variations affect drug metabolic pathways. In some cases this may result in sub-optimal therapeutic levels, or conversely, toxic adverse effects.

In the case of cancer treatment, the mutations acquired in a person’s tumour (non-heritable) may make the tumour more sensitive or resistant to treatment targeted gene, or gene pathway, specific treatment

Pharmacogenetics is the study of the role that DNA variants play in drug efficacy. The DNA variants may either be inherited, and part of an individual’s inherited genetic make-up, or may be acquired in a person’s tumour (non-heritable) and can be used to predict drug responses or the likelihood of adverse drug reactions.