To discuss PGx, we must first define two terms:
- Polymorphism
- Cytochrome P450 (CYP450)
A polymorphism is a variation in a specific gene (allele) that affects at least 1% of the population. It is essentially a mutation that occurs relatively frequently in the population.
CYP450 refers to a family of enzymes found predominantly in the liver. CYP450 enzymes work on various substrates (in this case, drugs), altering their chemical structures to facilitate excretion in the urine and feces. Many polymorphisms occur in the protein sequences of CYP450 enzymes. Recall that earlier, we stated that the liver has enzymes that will attach chemical groups onto drug molecules to make them more water soluble to facilitate their excretion. These are the reactions that the CYP450 enzymes facilitate.
