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Genetic Alliance; The New York-Mid-Atlantic Consortium for Genetic and Newborn Screening Services. Understanding Genetics: A New York, Mid-Atlantic Guide for Patients and Health Professionals. Washington (DC): Genetic Alliance; 2009 Jul 8.

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Understanding Genetics: A New York, Mid-Atlantic Guide for Patients and Health Professionals.

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Pharmacogenomics and Pharmacoegenetics

The impact of genetic makeup on drug response and outcome has been known since the 1950s. Interest reignited with the sequencing of the human genome, leading to the field now commonly known as pharmacogenomics. Genetic variation in drug targets or genes involved in drug disposition are known to result in different drug responses and outcomes for a given group of patients treated with the same drug. Many genes are likely to influence a single drug response (pharmacogenetics) and obtaining the big picture of the impact of gene variation on drug efficacy and safety has become a cornerstone of drug development.

The findings from genetic studies facilitate drug discovery and allow drug makers to produce treatments better targeted to the cause of specific conditions. This accuracy not only maximizes therapeutic effects but also decreases damage to nearby healthy cells. Pharmacogenetics aims to improve the likelihood of positive outcomes and reduce the risk of serious adverse responses. Pharmacogenetics has the potential to dramatically reduce healthcare costs associated with the more than 2 million hospitalizations and outpatient visits due to adverse drug responses and multiple drug prescriptions each year in the U.S.

Such knowledge allows physicians to tailor drug treatment to an individual’s genetic makeup, sometimes referred to as “personalized medicine.” Although environment, diet, age, lifestyle, and health status can all influence a person’s response to medicines, understanding an individual’s genetic makeup can be the key to prescribing the best available drug therapy from the beginning rather than relying on the traditional trial-and-error method of matching patients with the right drugs.

A number of research and clinical trials are performed for genes involved in drug dosage and response. The most well-known example of a pharmacogenetic intervention involves cytochrome p450 (CYP 450). The CYP 450 family of liver enzymes is responsible for breaking down more than 30 different classes of drugs. DNA variations in genes that code for these enzymes can influence their ability to metabolize certain drugs. Less active or inactive forms of CYP enzymes that are unable to break down and efficiently eliminate drugs from the body can lead to drug toxicity. Currently, panels offering testing for several of the “P450s” are available to patients to determine how effectively they metabolize specific drugs. Those identified as “poor metabolizers” may experience side effects, overdose at a standard dosage, or not receive any relief of symptoms. Such information is valuable in choosing drugs to treat very serious conditions from bleeding disorders (Warfarin) to breast cancer (Tamoxifen).

Despite the successes of pharmacogenetic testing for CYP 450 and identifying the correct drugs for some cases of cancer and HIV, this new field has highlighted the complexity of the interactions between drugs and biochemicals in the body. Understanding the role of genetics in common, chronic conditions remains hopeful; but with many new medical advances, it will take time for pharmacogenomics to enter the mainstream as a standard clinical tool.


  1. Licinio J & Wong M (eds). Pharmacogenomics: The Search for Individualized Therapies, Weinheim (Germany): Wiley-VCH; 2002.
  2. National Center for Biotechnology Information. One size does not fit all: the promise of pharmacogenomics. www.ncbi.nlm.nih.gov/About/primer/pharm.html.
  3. National Institute of General Medical Sciences, National Institutes of Health. Medicines for you. publications.nigms.nih.gov/medsforyou (Spanish language: publications.nigms.nih.gov/medsforyou/index_esp.html)
  4. Rothstein M (ed). Pharmacogenomics: Social, Ethical, and Clinical Dimensions.Hoboken (New Jersey): John Wiley & Sons. 2003.
Copyright © 2008, Genetic Alliance.

All Genetic Alliance content, except where otherwise noted, is licensed under a Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Bookshelf ID: NBK115549
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