Studies Find Genetic Link for Chronic Fatigue Syndrome
Chronic fatigue syndrome likely is caused by a group of five or more genetic and environmental causes, according to CDC studies published on Thursday in the journal Pharmacogenomics, the Washington Post reports.
For the studies, researchers over two days examined 227 residents of Wichita, Kan., who underwent a series of blood tests, hormone studies, psychological examinations and sleep studies. About one-fourth of participants met the formal definition of chronic fatigue syndrome -- which is characterized by unexplained extreme fatigue, difficulty with memory and concentration, sleep disorders and chronic pain -- and one-fourth had milder chronic fatigue.
In addition, a third group of participants met the formal definition of chronic fatigue syndrome but also had melancholic depression, and a fourth group was healthy.
For one group of studies, researchers examined the activity levels of 20,000 genes involved in response to stresses such as infections, injuries or emotional trauma and found that several hundred were overactive or underactive in subgroups of participants with chronic fatigue syndrome. Other studies that involved 50 genes with minor "misspellings" find a link between five of the 500 genetic mutations examined and increased risk for chronic fatigue syndrome (Weiss, Washington Post, 4/21).
Researchers also found that, among at least four different forms of chronic fatigue syndrome, each which separate genetic profiles and symptoms, all involved five polymorphisms in three genes in about 75% of cases (Maugh, Los Angeles Times, 4/21).
The genes included those that affect serotonin and glutamate levels, which are linked with depression and stress. According to one study, the activity of 26 genes accurately predicted which of six forms of chronic fatigue syndrome participants had based on symptoms and other tests. However, the "correlations were weak" in most cases, and "the gene expression patterns alone could not accurately distinguish those whose symptoms had been diagnosed as the syndrome from those whose symptoms had not," according to the Post (Washington Post, 4/21).
Researchers also found that participants with chronic fatigue syndrome had high levels of hormone secretions, blood pressure and other responses to stress.
According to the AP/New York Times, the studies could help lead to improved diagnosis and treatment of chronic fatigue syndrome, as well as help predict risk for the disease (AP/New York Times, 4/21).
Suzanne Vernon, a researcher involved with the studies, said, "There is a clear biologic basis for CFS, and knowing the molecular damage involved will help us devise effective therapeutic intervention and control strategies" (Reichard, CQ HealthBeat, 4/20).
CDC Director Julie Gerberding said, "This is the first credible evidence for a biological basis for chronic fatigue syndrome" (Ricks, Long Island Newsday, 4/21).
Lucinda Bateman, a physician with the Fatigue Consultation Clinic, said, "It is very hard to treat an illness until you understand what it is physiologically," adding, "This is a very important foundation" for new treatments (Los Angeles Times, 4/21).
K. Kimberley McLeary, president and CEO of the Chronic Fatigue and Immune Dysfunction Association of America, said, "Pharmaceutical companies have been sitting on the sidelines because they have not been able to get their hands around CFS. This gives them something to latch onto" (Los Angeles Times, 4/21).
NPR's "Morning Edition" on Friday reported on chronic fatigue syndrome. The segment includes comments from Anthony Komaroff, a professor of medicine at Harvard University; William Reeves, a researcher involved with the studies; Vernon; and a U.S. resident with chronic fatigue syndrome (Silberner, "Morning Edition," NPR, 4/21).
The complete segment is available online in RealPlayer.