Genetic Medicine Making Inroads Against Disease

TUESDAY March 18, 2008 -- In fields as varied as heart disease, bone health and post-traumatic stress disorder (PTSD), an explosion of knowledge in genetics is poised to revolutionize medicine, said scientists gathered at a special news conference Tuesday.

The findings are highlighting why some people appear to be more vulnerable to certain illnesses than others -- and how they might be helped.

"People are trying to get a better understanding of disease causes and how genes underlie that," said Dr. Georgia Wiesner, director of the Center for Human Genetics at University Hospitals Case Medical Center in Cleveland. "Genetics and genomics are giving us a better biological understanding and then we can start to develop therapies."

Wiesner and others spoke at a conference to unveil results of a number of studies in the March 19 issue of the Journal of the American Medical Association, a theme issue focused on genomic medicine.

The identification of genes that are key to disease is greatly advancing diagnostics and scientific research, one expert said.

"There has been a big shift in the practice of genomic medicine. When genes are discovered, this translates very quickly into the availability of genetic tests," noted Dr. Maren T. Scheuner of the nonprofit RAND Corporation in Santa Monica, Calif. "Fifteen years ago, there were 100 genes for which tests were available. Today, there are about 1,500 of these genes. Things are really moving rapidly."

In one of the JAMA studies, scientists found that lowered activity of a gene called paraoxonase 1 (PON1), which is linked to HDL or "good" cholesterol, may be related to a higher risk of developing adverse cardiac events. The gene has both anti-inflammatory and antioxidant activities and had been shown to protect against atherosclerosis ("hardening of the arteries") in mice.

Although the findings will not immediately impact clinical practice, they do provide a focus for future research into both prevention and treatment of heart disease, said the study's senior author, Dr. Stanley L. Hazen, director of the Center for Cardiovascular Diagnostics and Prevention at the Cleveland Clinic Foundation.

"The test is not available for clinical practice, but the long-term impact is that we now have a way of helping to identify individuals who are at risk," he told reporters. "We also know a pathway that is mechanistically linked to the disease process. This serves as a way of focusing attention on this gene [for prevention and therapy]."

A second study of more than 37,000 participants found that variants of the LRP5 gene are associated with an increase in the risk of bone fractures (up to 20 percent), as well as lowered bone mineral density.

"This gene by itself changes the risk of osteoporosis only by a small amount," stressed lead author Joyce B. J. van Meurs, of the department of internal medicine at Erasmus Medical Center in Rotterdam, the Netherlands. She added that, going forward, "several genes need to be discovered to make a robust, useful clinical tool for osteoporosis and that's what we're going to do."

A third study found that adults who experienced abuse during childhood and who also have variations in the FKBP5 gene were at greater risk for symptoms of PTSD as adults. The gene is related to the stress response which, in PTSD, appears unable to turn itself down after a trauma or series of traumas, explained study co-author Rebekah G. Bradley of the departments of psychiatry and behavioral sciences at Emory University School of Medicine and the Atlanta VA Medical Center.

The study was conducted in a low-income, urban population of Atlanta where 25 percent of participants reported symptoms consistent with PTSD -- high even when compared to rates experienced by recently returned combat veterans from Iraq.

The stress-linked gene variations "may predict both risk and resilience to PTSD among survivors of [childhood abuse]," Bradley explained. "The gene was not related to depression," she added.

Still, putting genomics into everyday medical practice is in its infancy, Scheuner's study suggested. Her team at the RAND Corporation found that the healthcare workforce is woefully unprepared for the dawning genetic area, especially as more tests are developed for common diseases.

"We need to educate the workforce about the role of genetics in disease and risk assessment and the potential for new therapeutics, and we need to think about training more genetic professionals who have a background in adult medicine," Scheuner said. "We need to understand how this information is going to fit into the way we practice medicine, how it makes a difference for patients, and how best to deliver services."

More information

There's more on genomics at the National Human Genome Research Institute.

Posted: March 2008


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