New evidence that genetics are responsible for Chronic Fatigue Syndrome

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Research published in the April 2006 issue of the journal Pharmacogenomics presents the first scientific evidence that genetics are responsible for Chronic Fatigue Syndrome.

The groundbreaking study, called the CFS Computational Challenge, or C3, was developed by the Center for Disease Control and Prevention’s principal CFS researchers, Dr. Suzanne Vernon and Dr. William Reeves. This is the most detailed and comprehensive clinical study on CFS to date, and, says Dr. Julie Gerberding, Director of the CDC, presents “the first credible evident of a biological basis for chronic fatigue syndrome.”

C3 evaluated a sample of the population of Wichita, Kansas, of which 227 participants had CFS. Participants in the study underwent a series of tests including detailed clinical evaluations, measurements of sleep physiology, cognitive function, autonomic nervous system function, blood and urine testing.

Four individual teams, each comprised of medical experts, molecular biologists, mathematicians and engineers, independently examined the resulting 500 clinical measures and 20,000 measures of gene expression, the process by which genes regulate cell activity.

Their findings, published in a collection of 14 papers released last week, demonstrated that CFS patients were twice as likely to have high levels of allostatic load as people who did not have CFS. Allostatic load is a complex stress measure of hormone secretions, the accumulated wear and tear on the body.

Additionally, Dr. Reeves said, CFS patients consistently exhibited particular genetic sequence variations “in certain genes that are related to those parts of the brain activity that mediate stress response.” Those individuals with CFS “have different gene activity levels that are related to the body’s ability to adapt to challenges and stresses that occur through life, such as injury and trauma,” continued Dr. Reeves.

The genetic variations between those individuals with CFS and those without the disease occur in the hypothalamus-pituitary-adrenal axis (HPA), which affects the body’s ability to withstand stresses such as injury and infection.

“Our working hypothesis is that the HPA axis and the brain is (sic) a plastic organ which changes its actual physical architecture, depending on how stress is accumulated over a lifetime,” Dr. Reeves explained. “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.”

Researchers identified at least three very different molecular profiles, or subtypes, of CFS. Distinction between the classifications includes genetic variations, and symptoms of the patient. The first group was characterized by extreme fatigue; the second was characterized by heart-rate variability, differences in cortisol, and sympathetic nervous system differences; the third was primarily menopausal women. “We targeted about 50 genes and about 500 polymorphisms in genes that are active in the HPA axis,” said Dr. Vernon. “Of those 500 polymorphisms, five on three genes were very important, not by themselves, but together: the glucocorticode receptor, the serotonin, and tryptophan hydroxylase. The three genes distinguished the three fatigued groups from those that were not fatigued, and two of those genes distinguished between the fatigued groups.”

This research is part of a cluster of studies published since September, 2005, which indicate that genetics are a contributing factor to CFS. Although there have been several studies over the last decade identifying certain physiological traits of CFS patients, heretofore they have failed to identify traits that are common to all CFS sufferers.

The results of the C3 study are good news for those dealing with CFS. The findings will increase the ability to predict who is susceptible to the disease, and mark an important step forward in CFS research. “Knowing the molecular damage involved will help us devise effective therapeutic intervention and control strategies,” said Dr. Vernon, and will “help us identify better ways to more effectively diagnose the illness, and to come up with more effective treatments,” continued Dr. Reeves.

The next step is to attempt to replicate these results in another study. First, the CDC is taking a different approach to analyzing the Wichita sample, with the aim of verifying the results. Currently, a team of researchers are collecting data on CFS from a population sample of 30,000 people in Georgia.

Later this spring, the CDC is launching a media and education campaign to promote CFS awareness. “There is no questions that chronic fatigue syndrome is a real condition,” says Dr. Reeves. “It is a serious public health problem. Most people aren’t aware they have it. A lot of the stress of our research is getting them into treatment.”

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