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What is pharmacogenomics?

Pharmacogenomics is the study of how genes affect a person’s response to drugs. It combines pharmacology and genomics to develop effective, safe medications and doses that are tailored to a person’s genetic makeup.

Many drugs that are currently available are “one size fits all,” but they don’t work the same way for everyone. It can be difficult to predict who will benefit from a medication, who will not respond at all, and who will experience negative side effects or adverse drug reactions.

Adverse drug reactions are a significant cause of hospitalizations and deaths in the United States. With the knowledge gained from the Human Genome Project, researchers are learning how inherited differences in genes affect the body’s response to medications. These genetic differences can be used to predict whether a medication will be effective for a particular person and will help prevent adverse drug reactions.

Potential benefits of pharmacogenomics:

  • More powerful medicines: Drugs may be developed targeting specific health problems that will maximize therapeutic effects but decrease damage to nearby healthy cells.
  • Safer drugs the first time: Doctors could have an idea which drug to use based on a genetic profile versus trial and error, decreasing the likelihood of adverse reactions.
  • More accurate methods of determining dosages: Instead of dosages being based on body weight and age, it would be based on an individual’s genetics. This would decrease the likelihood of an overdose.
  • Shared Decision Making: Patients are more likely to participate in their own care when they know their medications are safe and effective. This level of participation can significantly improve medication adherence and ultimately outcomes.

Pharmacogenomics in practice:

Small differences in the DNA code that influence a response to certain drugs are more common in certain population groups than others. For example, the effects of drugs called ACE inhibitors (angiotensin converting enzyme inhibitors) that improve symptoms and survival in cases of heart failure have been found to be greater in people of European or UK ancestry than African-Americans.

Some drugs act by binding to specific receptor sites, on the surface of or within body cells. Variation in the genes that code for the receptors may mean that some people may produce receptors that do not interact well with the drug. For example, some people have a lack of response to the drug salbutamol, used in the treatment of asthma, due to genetic variation in the gene that codes a receptor on the surface of smooth muscle cells lining airways of the lungs.

Genes may also determine how many of the receptors are produced on or within cells and genetic variation may mean that some people produce more of these sites than others. For example, the action of the widely used antipsychotic drug haloperidol (Haldol) depends on its ability to bind to the dopamine (D2) receptor site. In one study, 63% of patients whose genetic make-up caused a large number of these receptor sites to be produced had a response to treatment with haloperidol whereas only 29% of patients with a smaller number of dopamine (D2) receptor sites did well on the drug.

How people absorb, break down and metabolize drugs in the body can also be impacted by their genes. For example, some pain relief medications such as codeine require a protein produced in the liver called CYP2D6 for the drug to be used by the body, break it down and remove it. Variations in the information contained in the CYP2D6 gene determine how much of this enzyme is produced in the liver. People who have low levels of the enzyme metabolize codeine slowly and so it will be in the body for a longer period of time and is more likely to cause side effects.

Pharmacogenomics Resources for Prescribers

The FDA provides a list of therapeutic products from Drugs@FDA with pharmacogenomics information found in drug labeling. https://www.fda.gov/Drugs/ScienceResearch/ucm572698.htm

Other Resources:





Dr. Kerri Miller
Founder, Make People Better
Illness Recovery Scholar
Springfield, MO

Published on 11/1/17

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