What Is Precision Medicine?

For years, doctors and researchers have known that people diagnosed with the same disease (breast cancer or high blood pressure, for example) can have very different responses to particular treatments.

They now know that many of these differences are related to genes — the pieces of DNA carried on our chromosomes that help determine our individual characteristics (like height and hair color). In some cases, by using new and more powerful tests that reveal a person's unique genetic makeup, doctors can individualize treatment for a person's health problem, making the therapy safer and/or more effective.

This overall approach to health care is called precision medicine (or "personalized medicine" or "genomic medicine").

What Is Pharmacogenomics?

Pharmacogenomics (also called "pharmacogenetics") is the science of understanding the role of genes in determining the response a person may have when given a drug.

In some cases, doctors can use pharmacogenomic knowledge as one of the tools for practicing precision medicine. By knowing how someone's genes might affect how the body will handle or respond to a particular drug, a health care provider might change the type or amount of medicine given. This may lead to a better health outcome or make dangerous side effects less likely.

How Does Pharmacogenomics Work?

Differences in someone's genes (or "pharmacogenome") can affect how the person responds to a drug in a number of ways:

• How the drug is metabolized (how the drug is broken down and disposed of by the body). For example, if the body breaks down a drug too quickly, the level of drug in the body may be too low to treat the condition properly.
• How the body's cells respond to the drug. Gene differences can make the body tissues and organs less sensitive to the effects of the drug.
• How likely the person is to have a bad reaction to the drug. Some genetic tests can help identify who is at greater risk for rare but serious side effects.
• How effective a drug will be in treating someone with cancer. For example, knowing the genetic changes present in a person's leukemia or breast cancer cells can help doctors choose which drugs are most likely to get the best results.

Will Doctors Use Pharmacogenetic Testing Right Now?

Use of pharmacogenomic information to select a drug or dose of drug in the clinical setting is progressing rapidly and is available mostly in large metropolitan medical centers.

Most genetic tests of this type are considered experimental and may not be reimbursable by insurance plans. As a result, cost concerns have slowed progress in the use of pharmacogenetics to guide treatment. But major improvements in technology and strong clinical results are expected to help bring down these costs in the near future.

If you have questions about the possible role of pharmacogenomics in your child's care, talk with your doctor.

Reviewed by: Kathryn V. Blake, PharmD, BCPS;Vicky Funanage, PhD
Date Reviewed: 17-10-2017