Personalized medicine, also referred to as precision medicine, holds great promise to improve healthcare. According to the National Cancer Institute, personalized medicine integrates “information about a person’s genes, proteins, and environment to prevent, diagnose, and treat disease.” As the cost of genetic analysis decreases and research advances, it is becoming increasingly possible to include a person’s genetic make-up in the repertoire of tools that inform his or her healthcare. Personal genome sequencing has been used to diagnose children with rare conditions when other approaches have failed and has been applied in efforts to predict a person’s susceptibility to a medical condition. In addition, a growing number of medications are prescribed based on a person’s genetic make-up.
Your personal genome
What are genotype & phenotype?
Benefits and risks
The stories of Nic Volker and the Beery twins have garnered much attention about the potential for personal genome sequencing to advance healthcare. Nic Volker is the first child to receive a diagnosis and successful treatment as a result of genome sequencing. Nic, now thriving, had been terribly sick with a rare, undiagnosed medical condition and endured over one hundred surgeries by age 4. A portion of Nic’s genome was sequenced to look for a genetic mutation that caused his illness, which led to a diagnosis and pointed doctors towards a treatment. The Beery twins, Noah and Alexis, were misdiagnosed with cerebral palsy as babies. Years of medical treatments, mysterious symptoms and a search for answers ensued. After having their genomes sequenced as teenagers, they were accurately diagnosed and successfully treated.
How might personalized medicine change how drugs are prescribed? What is pharmacogenomics?
A major goal of personalized medicine is to tailor treatments, using a person’s genetic make-up to identify medications that will be most effective with minimal side effects. Traditionally, doctors prescribe a medication and then wait to see how the patient responds; some will respond positively, some will not respond at all, and some will have a negative reaction and suffer side effects. It is estimated that nearly 70% of Americans take at least one prescription medicine, and there are many questions about the risks of medications that are overprescribed, underused or given to people for whom the drug is not working as hoped.
The field of pharmacogenomics is exploring how people’s genes impact their response to medications. According to the National Institutes of Health’s Genetics Home Reference, “this relatively new field combines pharmacology (the science of drugs) and genomics (the study of genes and their functions) to develop effective, safe medications and doses that will be tailored to a person’s genetic makeup.” A number of drugs, including those that can treat HIV, cystic fibrosis, depression and a number of types of cancer, have pharmacogenomic information in their label regarding an individual’s genetic make-up. With genetic testing before treatment, people may avoid medications that will cause harm or be ineffective, and hopefully find the drug that will most effectively treat their illness.
In some cases, drugs are intended only for people with a specific genetic make-up. Kalydeco is a cystic fibrosis drug that was approved in the United States in 2012 to treat the 4% of cystic fibrosis patients who harbor a specific mutation in the CFTR gene. Similarly, a number of cancer therapies are designed to target cancers that have acquired specific genetic mutations.
Your genetic make-up can also influence how quickly you break down or metabolize certain drugs, which may make the same dosage of a medication work for one person, but ineffective or toxic for another. Warfarin, commonly known as Coumadin, is an anticoagulant used to prevent blood clots and is an example of a widely prescribed and successful drug for which the dosage can be adjusted based on genetic markers that influence a person’s metabolism. The medical community is not uniformly aligned on the benefits of genetic testing for warfarin dosing, and research is continuing to examine whether genetic testing is helpful in finding the most safe and effective dose for patients and reducing the frequency of adverse reactions and hospitalizations. The field is still developing, and a targeted drug therapy approach informed by genetic testing will not yet work for every patient.
If you are looking to teach these concepts to students or seeking more depth, please see pgEd’s lesson plan on personalized medicine.
- “Questions persist about who pays for genetic testing,” June 2014, pgEd Blog.
- “Gene test helps patients avoid thyroid surgery,” by Susan Young, February 2014, Technology Review.
- “Personalized Medicine may be Good for Patients but Bad for Drug Companies Bottom Line,” by Henry I. Miller, September 2013, Forbes.
- “Smarter medication could save $213B in health care costs,” June 2013, The Associated Press.
- “Research aims to improve personalized cancer care,” September 2012, pgEd Blog.
- “In Treatment for Leukemia, Glimpses of the Future,” by Gina Kolata, July 2012, New York Times.