It has been said that we now live in a new era of "personalized medicine", "individualized medicine" or "precision medicine." As genetic testing becomes ubiquitous and more and more genetic risk markers, and therapeutic response markers are discovered, we move closer to realizing the 'personalized medicine' approach. Personalized medicine refers to the testing of a patient's genotype (or a tumor's genotype) in order to customize the clinical care the patient receives. Pharmacogenomics (PGx) has begun to play a role in this advance toward personalized medicine. PGx is the study of how individual variations in the human genome affect responses to medications.
The term "pharmacogenetics" has also been used, as a synonym for PGx.
The primary reason that individuals respond to drugs differently is due to the fact that there are often changes within the genes of receptor proteins and in the enzymes that metabolize drugs. These changes can affect the pharmacokinetics of drugs and the pharmacodynamics of drugs. Such mutations (or polymorphisms), contribute to the differences we see between patients and the efficacy or toxicity of a given drug. In PGx, these mutations are referred to as variants. PGx offers the ability to test patients for genetic variants that can, or will, affect the disposition of drugs in the body.
