Protein May Lead to First Test for Chronic Fatigue Syndrome
Feb. 16, 2000 (New York) -- It's been labeled everything from a stress disorder to the "yuppie flu," but a study in the February issue of The American Journal of Medicine suggests that chronic fatigue syndrome (CFS), for which there is no real diagnostic test, causes changes to the immune system that can be seen in the blood of sufferers. The findings could help lead to a test to diagnose CFS and to distinguish patients with CFS from those with other disorders characterized by chronic fatigue, such as fibromyalgia and depression.
CFS surfaced in the mid-1980s when physicians in resorts and towns near Lake Tahoe began seeing a small cluster of people, primarily women, with similar, debilitating flu-like symptoms that included low-grade fever, body aches, short-term memory loss, sleep disturbances, and fatigue that persisted for months.
According to the CDC, chronic fatigue symptoms now affect more than 14 million people between the ages of 17 and 69. CFS is twice as common in women as in men. Diagnosis is often difficult because most laboratory tests show normal or near-normal results and serve only to rule out conditions with similar symptoms, such as thyroid disease. For years, researchers have looked for markers that would point to defects in the immune system that might cause CFS. Such signs could not only further understanding of how CFS affects the body, but also help legitimize the existence of a disease that some in the medical community question.
In the new study, Kenny De Meirleir, MD, PhD, and colleagues from the Vrije University of Brussels, Belgium, looked for the presence of a protein known as 2-5A binding protein in the blood of 57 people who had had CFS for an average of seven years. They compared blood samples from these patients with blood from healthy subjects and patients with fibromyalgia or depression.
The protein was found in 88% of CFS patients, 38% of fibromyalgia patients, 32% of healthy people, and 14% of depressed patients.
According to the researchers, the protein is directly involved in the immune system's ability to fight viruses that can invade the body. Up to 90% of patients with CFS report that their symptoms started after a viral infection. This has led some researchers to suggest that certain viruses may actually cause CFS. But others say a dysfunction of the immune system that causes it to fail to respond, or to over-respond, to invading viruses may lead to CFS symptoms.
De Meirleir and colleagues cannot say, based on the small size of their study, how many people with CFS have the defective immune-system component that leads to the presence of the protein in their blood. Further research also is needed to determine whether the immune dysfunction "is associated with a particular stage of the illness or if it fluctuates over time," they write.