Understanding human genetic variation and how it impacts on gene function is a major focus in genomic-based research. Translation of this knowledge into clinical care is exemplified by pharmacogenetics/pharmacogenomics. The identification of particular gene variants that might influence drug uptake, metabolism, distribution or excretion promises a more effective personalised medicine approach in choosing the right drug or its dose for any particular individual. Adverse drug responses can then be avoided or mitigated. An understanding of germline or acquired (somatic) DNA mutations can also be used to identify drugs that are more likely to be therapeutically beneficial. This represents an area of growing interest in the treatment of cancer.