Could affect body's ability to endure stresses such as injury, infection, researchers say
By Amanda Gardner
HealthDay Reporter
THURSDAY, April 20 (HealthDay News) -- U.S. scientists have identified certain genetic traits common to people who suffer from chronic fatigue syndrome (CFS), strongly suggesting a genetic basis for the condition.
The genetic make-up identified by the researchers involves the body's ability to adapt to change and to withstand common life stresses such as injuries and infections.
"This really is the first credible evidence of a biological basis for chronic fatigue syndrome," Dr. Julie Gerberding, director of the U.S. Centers for Disease Control and Prevention, said at a Thursday press conference. "It reflects the remarkable confluence of a number of scientific advances that are coming to bear on a problem of great importance to many people in the U.S. It's an important step forward in the field of chronic fatigue syndrome research."
The information should one day translate into better ways to diagnose and treat chronic fatigue syndrome, added Dr. William Reeves, the CDC's lead CFS scientist, at the same conference.
Outside experts noted that this research really builds on other findings over the last decade, which had already uncovered evidence of physiological markers for CFS.
"Over the last decade, there have been a number of investigators who have found some very intriguing things," said Leonard Jason, professor of psychology at DePaul University in Chicago and director of DePaul's Center for Community Research. "The problem is they don't occur in 100 percent of cases. We've got many different subsets and we need to start looking at these groups that have different biological aberrant patterns."
More than one million people in the United States are estimated to suffer from CFS, costing the nation some $9 billion annually, and each family $20,000 per year in lost earnings. The condition is more common in women aged 40 to 60 and is marked by a cluster of debilitating symptoms, including unexplained fatigue, problems sleeping, problems with memory and concentration, and pain. CFS can be as disabling as multiple sclerosis.
The illness was first recognized in the late 1980s and, initially dubbed the "yuppie flu," suffered from a credibility crisis. "One of the common stereotypes is that this is a bunch of hysterical, upper-class, professional, white women," Reeves said.
The condition remains a mysterious one. "Despite more than two decades of basic and clinical research and at least 3,000 peer-reviewed papers, we're still learning a lot about it," said Reeves.
The CDC findings appear in a series of 14 research papers released Thursday by the agency and published in the April issue of Pharmacogenomics.
The research, called the CFS Computational Challenge, or C3, involved a group of 227 people with chronic fatigue syndrome in Wichita, Kan. Participants spent two days in a hospital research ward undergoing extensive tests, including clinical evaluations, measurements of sleep physiology, cognitive function (memory and concentration), autonomic nervous system function, and blood evaluations that featured an investigation of the activity of 20,000 genes.
Four different teams comprised of scientists from a number of different disciplines then looked at the data independently.
The teams found that "people with CFS have certain genes that are related to those parts of the brain activity that mediate stress response, and they have different gene activity levels," Reeves said. "This is related to the body's ability to adapt to challenges and stresses that occur through life such as injury and trauma."
Dr. Suzanne Vernon, the molecular epidemiology team leader for the CFS Research Laboratory at the CDC, added: "There are differences in the actual genetic make-up, in the DNA code, that probably results in differences in gene activity and in the manifestation of the illness itself. We've brought together a whole bunch of different types of data -- genetics, gene activity, clinical information, physiological markers, ways to describe how the person is feeling -- and wrap that all tighter to try to generate a molecular profile."
What seems clear is that CFS is a heterogeneous disease. "It's probably not just one diagnosis," Vernon said. "We have demonstrated that there are probably at least four or five molecular profiles or groups of people that make up this complex of CFS."
Specifically, the scientists think the hypothalamus-pituitary-adrenal axis (HPA) is involved in the disorder. "This is a physiologic marker of accumulated adaptation to stress," Reeves said. "Our working hypothesis is that the HPA axis and the brain is a plastic organ which changes its actual physical architecture depending on stresses accumulated over the lifetime. To some extent, genetics determine how you react to these stressors and, more important, they actually determine your subsequent reaction to stress later during the life span."
Although the researchers weren't specific on when this information would translate into diagnostic and treatment gains, patients may already be seeing some benefit.
"From the patient point-of-view, data like this is good because it gives them more legitimacy," DePaul's Jason said. "CFS patients are looking for biological substantiation of what they feel."
But the science behind the new findings still needs to be replicated, Jason added. "Science has to be careful about any particular group of findings," he said. "We've got to have it replicated and it's probably going to be a little while before the shake-out occurs and we can say this is good science or not. Now it's like the Wild West. It's new and exciting."
The CDC is currently in the process of collecting more data on chronic fatigue syndrome from people in Georgia.
SOURCES: Leonard Jason, Ph.D., professor of psychology and director, Center for Community Research, DePaul University, Chicago; April 20, 2006, teleconference with Julie Gerberding, M.D., director, U.S. Centers for Disease Control and Prevention (CDC), Atlanta; William Reeves, M.D., director, CFS public health research program, CDC, Atlanta; Suzanne Vernon, M.D., molecular epidemiology team leader, CFS Research Laboratory, CDC, Atlanta; April 2006, Pharmacogenomics
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