History of Pharmacogenetics
Pharmacogenetics, the study of hereditary variations in drug response, is a term that first appeared in the literature in the mid-1950s. Advances in genetics, including the sequencing of the human genome, have led to a better understanding of how hereditary variation in drug metabolism, transport and response can be applied to individualized patient care through diagnostic testing.
The human genome sequence enabled comparisons of genetic sequences between individuals and led to the discovery that the nucleotide sequence for many if not all human genes exhibit a natural rate of variability. This characteristic is referred to as genetic polymorphism. Genetic polymorphism can occur in the form of single nucleotide substitutions, insertions, or deletions (single nucleotide polymorphisms, or SNPs). Short stretches of repetitive nucleotide sequences, complete gene deletion and gene duplications are the basis for our individual physical characteristics, including the way we respond to specific medications.
Variants often occur in enzymes that are not essential to development or normal metabolism and not required for vital functions. Deficiencies may therefor go unnoticed until a medication proves ineffective or even harmful at standard dosing. The best-known examples of these types of enzymes are members of the cytochrome P450 (CYP) gene family. When drugs which are substrates for the variant CYP enzymes are medically indicated, the choice to perform a test to identify gene characteristics which can inform your therapeutic decisions may dramatically improve patient care. Pharmacogenetic testing can help reduce adverse drug reactions, save time and money, and strengthen the patient-physician relationship.