Pharmacogenomics is the study of how genes influence a person's pharmacological response. This relatively new area combines pharmacology (drug science) and genomics (the study of genes and their functions) to create effective, safe therapies and doses that are personalized to a person's genetic makeup. Pharmacogenomics is a pre-requisite for tailored medicine. It also combines pharmacology and genomics to learn how heredity affects the human body's medication response (classically correlating gene expression or SNPs with drug efficacy). Pharmacogenomics is still in its preliminary stages. Its application is currently limited, but novel ways are being investigated in clinical trials.