Genomic and Personalized Medicine: A Primer
Every human being has a unique genome that carries the complete set of genetic instructions needed for the growth, development, and maintenance of his or her body.
While all people share an overwhelming majority of these instructions, each set contains individual differences that influence a nearly infinite array of personal characteristics.
Genomic medicine is a rapidly advancing field that takes advantage of the one-of-a-kind information from people’s genomes to guide, or personalize, their medical treatment.
What Is a Genome?
The word genome refers to the complete set of instructions written in the DNA of each and every living thing on the planet -- from oak trees to fruit flies to human beings. DNA is composed of four chemicals that are repeated countless times in many different sequences.
The names of the DNA chemicals are abbreviated as A, T, C, and G, which is why DNA sequences often are referred to as four-letter codes.
The sequence of these four letters dictates the type of organism that develops and gives that organism distinct physical and physiological traits and tendencies. The human genome contains approximately three billion pairs of these DNA chemicals, and learning the correct sequence of all three billion pairs was a primary goal of the Human Genome Project.
Interestingly, genes are thought to comprise only about two percent of the human genome, with the rest consisting of “non-coding” regions, believed to regulate the function of genes and contribute to the structural integrity of chromosomes.
The Human Genome Project
After 13 years of research, the Human Genome Project was completed in 2003 by the U.S. Department of Energy and the National Institutes of Health. The Project’s overarching goal was twofold: to learn the order of the three billion units of DNA that comprise a human genome and to identify each of the genes discovered in that massive amount of data.
By 2003, nearly all of the pairs of chemicals that make up the DNA units had been put into the correct sequence. The individual genes within the long strands of DNA, and the elements that control the genes, are still in the process of being identified. Current counts indicate that the human genome contains 22,000 to 23,000 genes.
The Human Genome Project also confirmed that on a genomic level, approximately 96 percent of genetic material is identical in all human beings. A portion of the remaining material influences traits such as people’s likelihood of developing (or not developing) certain medical conditions, as well as how their bodies respond to treatments for those conditions.
The completion of the Human Genome Project -- and the resulting mapping of the human genome -- was a monumental, eagerly anticipated leap forward…one that has the potential to change the biomedical and health care landscape worldwide.
In the years since the completion of the Human Genome Project, scientists already have uncovered hundreds of areas in the genome where differences among individual genetic codes can influence people’s risk for developing diseases ranging from diabetes to psoriasis to heart disease.
Frequently Asked Questions about Genomic Medicine
How can the human genome impact health care?
Genomic medicine is about using a person’s unique genetic data to inform and tailor the health care he or she receives. Scientists now have the technology to build a genetic profile for any individual -- similar to a fingerprint -- for each person’s genetic blueprint. By examining this blueprint, they can show how one person is different from another at the most basic level.
Scientists can use this information to learn how genetic differences are related to differences in health, predisposition to disease, and response to treatments. Physicians can now obtain “profiles” of genetic information from a DNA sample using “gene chips” that can provide insight into many health and disease issues at once.
There also are other methods that allow physicians to use gene-chip technology to assess the activities of genes in certain tissues and even in blood. These genomic methods also can provide important information about disease prognosis and predict responses to drug therapy.
The power of genomic medicine is that these profiles may soon enable scientists and physicians to assess a person’s susceptibility to serious diseases such as cancer, heart disease, and Alzheimer’s disease; to determine the probability that a particular treatment will or will not be effective in treating those conditions; and therefore, to precisely tailor medical treatment to individuals with greater accuracy than ever before.
Early in the Human Genome Project, scientists hoped to isolate specific genes that significantly influence the development of common diseases. Genes, however, are only part of the equation, as most diseases are the result of multiple genes interacting with one another, as well as with environmental factors.
Even so, the information garnered from the Human Genome Project has the potential to forever transform medicine -- from health to disease and prevention through treatment. Many within the biomedical community believe that genome-guided medicine is the future of health care -- the next logical step in a world in which more is known about human genetics, disease, and wellness than ever before.
Genomic medicine aims to offer these advantages to patients and clinicians:
- Higher chance of desired treatment outcomes
- Lower chance of harmful side effects from treatment
- Better health care planning tailored to individual risks
- More focused treatments based upon individual characteristics; less trial and error
- Reduced costs for health care systems
- Better patient health and health care
- Reduction of the time, cost and failure rate of clinical trials
- Revival of drugs that have failed clinical trials, but that might be useful for some individuals
Can healthy people benefit from personalized medicine?
Absolutely. Because a person’s genome influences his or her risk for developing (or not developing) a broad range of medical conditions, genome-guided medicine focuses strongly on wellness and disease prevention.
For example, if a person's genomic information indicates a higher-than-average risk of developing diabetes or a particular form of cancer, he or she may choose a lifestyle and/or take other precautions designed to help counteract that underlying risk.
What genomic medicine efforts are under way at Duke?
Duke Medicine’s commitment to advancing the field of personalized medicine is institution-wide and genomic medicine is essential to this. Exciting and promising research (including clinical trials) is ongoing in a number of specialties, and a network of multidisciplinary entities is involved in these efforts.
Learn more by visiting the Duke Personalized Medicine Web site.
