Genetics and Genomics: How Our Chemical Make-Up is Paving the Way

by Debbe Geiger, Duke Medicine News Office
June 2010

In recent years, news stories have heralded scientific discoveries of genes linked to a wide variety of conditions from common cancers to rare diseases. Researchers at Duke University Medical Center have been involved in many of these significant developments including discovering:

Genes that appear to increase people’s risk for developing the most common form of Alzheimer disease.
the BRCA1 and BRCA2 genes responsible for many inherited forms of breast and ovarian cancers.
the first major gene known to influence an individual’s risk for developing age-related macular degeneration, the leading cause of visual impairment and legal blindness in the elderly.

These and many other discoveries at Duke and elsewhere have set the stage for a new way of practicing medicine. It’s called Personalized Medicine.

How Personalized Medicine Works Everyone has a complete set of unique genetic instructions — written deep within their DNA — that influence an infinite array of personal characteristics, from their eye color to their height. By examining these fingerprints, scientists can see how people are different from each other at the most basic level.

They can also use the information to ascertain differences in their health, from their predisposition to disease to their response to treatments. Using sophisticated technology, researchers can delve even further to monitor the activities of these genes in certain tissues and blood. The answers the scientists derive help them discover how diseases progress, as well as how people will respond to drug therapy.

All that work lies under the area called personalized medicine. The rapidly advancing field takes advantage of the one-of-a-kind information from people’s genetic make-up to personalize their medical treatment. Its potential to change medicine are enormous and include:

Higher chances of desired treatment outcomes.
Lower chances of harmful side effects from treatments.
Better health care planning and disease prevention.
More focused treatments based upon individual characteristics.
Reduced costs for health care systems.
Better patient health and health care.

Who Benefits Personalized medicine isn’t just for people who are diagnosed with a disease. Healthy people can benefit as well, especially when doctors can use their genetic make-up to potentially identify a condition before it starts.

If, for example, an individual is shown to have a gene or set of genes that indicate whether a healthy person has a higher-then-average risk of developing diabetes, heart disease, a particular form of cancer or blood-clotting disorders. If detected, he or she may choose to make a lifestyle change and/or take other precautions designed to help counteract that underlying risk.

The Role of Genetic Testing
As a frontrunner in advancing personalized medicine, Duke University Medical Center offers a comprehensive array of genetic and genomic tests — and is leading the development of new tests and their integration into medical practice.

Perhaps most notably, Duke scientists have devised new methods for profiling cancerous tumors and applying those genomic "fingerprints" to select the therapies most likely to work for each individual patient.

The close proximity between Duke’s research labs and medical center enables the translation of those discoveries directly into improved patient care via a series of ongoing clinical trials in cancers that include lung, breast, and prostate.

(This growing battery of advanced tests is expected to become available to all cancer patients treated at Duke.)

For more information on genome-guided clinical trials at Duke, visit genomestohealth.org.

Types of Genetic and Genomic Tests A complete spectrum of genetic and genomic tests are available for a variety of individuals and circumstances. Clinicians consider the information they yield in conjunction with other clinical information to make informed treatment decisions for their patients. These tests, many of which are available at Duke, can be broken down into four broad categories:

Genomic health-risk testingGenomic health-risk testing can provide useful information about a person’s risk of developing medical conditions such as heart disease, cancer, diabetes, and vision loss. The information gleaned from such tests can help guide health behaviors and preventive screening.

Genomic health-risk testing is not diagnostic. In other words, it cannot determine whether a person has a particular medical condition; it can only be used to determine whether his or her genomic makeup contributes to a higher-than-average likelihood of developing that condition.

Pharmacogenetic testing can provide information about whether an individual, based on his or her genetic composition, is more likely to have a positive or negative response to a specific drug.

The information gleaned from pharmacogenetic testing can influence the types of drugs and dosages a physician prescribes to a particular patient. For instance, the FDA recommends that patients undergo genetic testing before they are prescribed the blood thinner warfarin.

Genetic testing may be used to help identify underlying causes of developmental and/or medical problems, as well as to determine if an individual is at risk for developing or passing on an inherited genetic syndrome.

There are many genetic conditions or syndromes, including inherited forms of heart disease, dementia, cancer, and vision loss; sickle cell disease; blood-clotting disorders; and connective-tissue disorders such as the Marfan syndrome.

Genome-guided cancer care uses the unique genomic profile of a cancerous tumor — rather than a genomic profile of an individual — to assist physicians in identifying the treatment plan and/or drugs most likely to be effective for each individual patient.

If you are concerned about your genomic or genetic health risks due to your family or personal health history, speak with your doctor or nurse to find out if there are steps you can take to address your unique health risks-such as modifying your diet or improving your fitness level — or whether you might benefit from more specific prevention plans, including medical screening and testing.

Where to Go for Genetic and Genomic Testing As the menu of available tests expands, primary care and specialist physicians are engaged in efforts to explore the value of these tests — such as those for common chronic conditions such as heart disease, breast and prostate cancer, diabetes, and blood-clotting disorders — in developing personalized plans for patients to make healthy and appropriate lifestyle changes, pursue additional screening tests, and optimize medication management.

For more information about Duke Primary Care practices that are ordering and interpreting genetic test results, contact Duke Primary Care at 888.275.3853 or visit DukeHealth.org.

If you are interested in participating in a study of genetic testing for diabetes risk in primary care, call 919.419.5920 or visit genomestohealth.org.

Medical Genetics Clinic Although it is housed within the Department of Pediatrics, the Medical Genetics Clinic sees patients of all ages for genetic evaluation of uncommon and/or inherited developmental and medical concerns, as well to evaluate family history of a genetic condition. The clinic conducts hundreds of different tests and offers dedicated programs in areas that include general genetics, cardiovascular genetics, autism, connective-tissue disorders, Down syndrome, Fragile X syndrome, and metabolic genetics. To learn more, call 919.684.2036

Hereditary Cancer Clinic The Hereditary Cancer Clinic, a component of the Duke Comprehensive Cancer Center, helps adults determine whether hereditary cancer syndromes run in their families. This involves discussion and in some cases, risk-assessment testing to identify changes in genes that increase one’s odds of developing certain cancers.

Because several cancers can be caused by one such change — and most cancers can be associated with a particular hereditary cancer syndrome — the HCC sees patients who have or are concerned about developing virtually every type of cancer, with breast, ovarian, and colon cancers being the most common.

For more information, call 919.684.3181.

Fetal Diagnostic Center Duke Medicine’s Fetal Diagnostic Center offers genetic counseling and education for pregnancy issues including advanced maternal age, abnormal tests and/or ultrasound findings, exposure to certain substances, thrombosis, multiple miscarriage, and infertility. For more information, call 919.684.3604.

Ophthalmic Genetics Program The Ophthalmic Genetics Clinic provides coordinated interdisciplinary diagnostic and management services for individuals with a personal or family history of a hereditary eye condition. To learn more, call 919.684.0584 and 919.684.9154.

Duke Executive Health Program The Duke Executive Health Program offers several genomic health-risk assessments as well as a specialized family history risk assessment to participants of its comprehensive health-assessment program. These include familial genetic-risk assessments and genomic health-risk testing.

To learn more, call 919.660.6606 or visit dukeexechealth.org.

Adult Cardiovascular Genetics Clinic The Duke Adult Cardiovascular Genetics Clinic offers novel techniques for identifying and diagnosing adults with a wide range of suspected inherited cardiovascular conditions — including hypertrophic cardiomyopathy, early-onset coronary artery disease, familial cardiomyopathy, long QT syndrome, and Brugada syndrome — as well as blood-clotting disorders such as Factor V Leiden and vascular diseases such as Marfan’s syndrome.

The clinic also provides genetics education and counseling services for patients and family members, and an infrastructure through which patients and families may participate in related clinical research at Duke. For more information, call 919.681.5816.

Insurance and Referrals
Insurance companies may cover the cost of genetic and genomic testing partially or in full. Check with your insurer for coverage specifics before tests are scheduled.

Some genetic- and genomic-evaluation services require that patients be referred by a physician; others do not. In addition, some types of genetic and genomic testing are available only within the framework of a clinical study; others are offered clinically.

For more information and links to helpful resources on genomics and personalized medicine, visit dukepersonalizedmedicine.org.