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What is Pharmacogenetics?

Pharmacogenetics is the study of how gene variants affect response to drugs, combining traditional pharmaceutical sciences and biochemistry with knowledge of genes, proteins and polymorphisms.

Pharmacogenetics is the study of how the actions of and reactions to drugs vary with the patient's genes.

- Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.

It began in the 1950s with a series of observations that indicated that genetic factors could alter some responses to drugs. In the 1970’s scientists discovered the heritable absence in many people of an important liver enzyme called debrisoquine hydroxylase (also known as the CYP2D6 enzyme). This enzyme metabolizes many medications. Cytochrome (CYP450) enzymes are responsible for metabolizing nearly half of all drugs on the market today and much effort has been directed at cataloging the P450 gene variants (polymorphisms) that cause individual variability in drug response.

Variations in a gene’s DNA sequence, called polymorphisms may result from a single nucleotide substitution‚ or the deletion or addition of nucleotides. These genetic changes in the DNA sequence can influence drug efficacy and side effects. Pharmacogenetics focuses on defining those genotypes to explain why some patients do not respond to high doses of a medication‚ while others have side effects or toxic reactions at low doses of the same medication.

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