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JAMA Patient Page
April 10, 2013

Genomic Medicine

JAMA. 2013;309(14):1544. doi:10.1001/jama.2013.1927

Genomic medicine, sometimes also known as personalized medicine, is a way to customize medical care to your body's unique genetic makeup. Each of the cells in the body contains DNA, the molecules you inherit from your parents that determine how your body looks and functions. DNA is arranged like a twisted ladder, with information stored in the arrangement, or sequence, of the rungs. Sections of the DNA ladder that contain information needed to make proteins are known as genes. The entire structure is the genome. A nearly complete map of the DNA sequence was completed in 2003, and since then, scientists have worked to understand how each gene functions and how it is coordinated with every other gene. The human genome may contain 20 000 to 23 000 genes.

WHAT IS GENOMIC MEDICINE?

Everyone responds to stress and the environment differently, and they also respond to disease and to treatments differently. Although greater than 99% of a DNA sequence is identical from person to person, the last 1% helps to explain these differences. Different people may have small variations in specific genes, and some people may have genes that others do not. These may increase susceptibility to a specific disease or provide protection from that illness. Scientists continue to discover new ways that subtle gene differences cause large differences in health. This understanding can lead to better ways to prevent, diagnose, and treat many types of health conditions.

Genomic medicine describes these efforts. Although genomic medicine is early in development, some areas where it has shown promise include

  • Risk assessment—for instance, women with a BRCA gene mutation (variation) are at higher risk of developing breast cancer than those without the mutation.

  • Early detection—individuals with mutations in genes that increase risk of colon cancer benefit from earlier and more frequent screening for colon cancer.

  • Diagnosis—for some types of heart disease, detection of a gene mutation can lead to diagnosis and treatment that can prevent sudden cardiac death before any symptoms occur.

  • Prognosis—for many types of cancer, including some types of lung cancer and leukemia, presence or absence of specific mutations means a higher likelihood of survival.

  • Tailored treatment—it is now understood that some of the variability in how people respond to medications is explained by the way their bodies interact with the drugs. The field of pharmacogenomics seeks to understand these differences. For some medications, identifying individual gene differences can help customize both the selection of medications and dosing for the best response.

CAUTIONS

There are many aspects to genomic medicine that society must consider. For instance, if a gene mutation causes a disease with no known treatment, does it make sense to test individuals for that mutation before they have symptoms? Also, some mutations cause an increased risk of illness, but that risk increase is very small in comparison with risks of other factors like diet and exercise. Does it make sense to test individuals for these types of changes when the change may not cause harm? How should this information be used? It is illegal for health insurance companies and employers to use genetic information to limit eligibility, set premiums, or discriminate against individuals without symptoms.

FOR MORE INFORMATION

INFORM YOURSELF

To find this and previous JAMA Patient Pages, go to the Patient Page index on JAMA 's website at www.jama.com. Many are available in English and Spanish.

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Article Information

Sources: National Institutes of Health. Burke W, Psaty BM. Personalized medicine in the era of genomics. JAMA. 2007;298(14):1682-1684.Hamburg MA, Collins FS. The path to personalized medicine. N Engl J Med. 2010;363(4):301-304. Wharton School of the University of Pennsylvania. The promise and perils of personalized medicine. http://knowledge.wharton.upenn.edu/article.cfm?articleid=3143.

The JAMA Patient Page is a public service of JAMA. The information and recommendations appearing on this page are appropriate in most instances, but they are not a substitute for medical diagnosis. For specific information concerning your personal medical condition, JAMA suggests that you consult your physician. This page may be photocopied noncommercially by physicians and other health care professionals to share with patients. To purchase bulk reprints, call 312/464-0776.

Topic: GENOMIC MEDICINE

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