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CFS stands for chronic fatigue syndrome. Chronic means persistent or long-term.

ME stands for Myalgic: my-AL-jik Encephalomyelitis: en-SEF-uh-lo-MY-uh-LY-tis.

Myalgic means 'muscle aches or pains'. Encephalomyelitis means inflammation of the brain and spinal cord. CFS/ME is a serious, disabling and chronic neurological illness affecting approximately 1 million people in the United States and as many as 17 million people worldwide.

CFS/ME is characterized by:

  • debilitating fatigue (exhaustion and extremely poor stamina)
  • neurological problems
  • and a variety of flu-like symptoms

The illness is also known as chronic fatigue immune dysfunction syndrome (CFIDS), In the past the syndrome has been known as chronic Epstein-Barr virus (CEBV).

The core symptoms include:

  • excessive fatigue
  • general pain
  • mental fogginess
  • often gastro-intestinal problems

Many other symptoms will also be present, however they will typically be different among different patients. These include:

  • fatigue following stressful activities
  • headaches
  • sore throat
  • sleep disorder
  • abnormal temperature
  • and others

The degree of severity can differ widely among patients, and will also vary over time for the same patient. Severity can vary between getting unusually fatigued following stressful events, to being totally bedridden and completely disabled. The symptoms will tend to wax and wane over time. This variation, in addition to the fact that the cause of the disease is not yet known, makes this illness difficult to diagnose.

In some cases, CFS/ME can persist for years. The cause or causes of CFS/ME have not been identified and no specific diagnostic tests are available. Moreover, since many illnesses have incapacitating fatigue as a symptom, care must be taken to exclude other known and often treatable conditions before a diagnosis of CFS/ME is made.

Genetic Link

William Reeves, M.D., director of CFS research at the CDC said, "For the first time ever, we have documented that people with CFS have (variations in) certain genes that are related to those parts of brain activity that mediate the stress response."

Also, people with the syndrome have differences in genetic activity levels that affect the way they respond to stress accumulated over a lifetime, Dr. Reeves said in a media telebriefing to announce 14 research papers arising from a CDC study in Wichita, Kan.

The findings could lead to better diagnostic tools for the syndrome, which is often regarded as ill-defined, and to better treatments, including both cognitive and behavioral therapies and new drugs, Dr. Reeves said.

The papers, published in the April 20, 2006 issue of the journal Pharmacogenomics, were described as "groundbreaking" by Dr. Reeves, but were not made available to reporters by the CDC.

The research "is really the first credible evidence of the biological basis for chronic fatigue syndrome," said CDC director Julie Gerberding. "It reflects a remarkable confluence of a number of scientific advances," she added.

The flurry of research papers arose from a longitudinal population-based study in Wichita, from 1997 to 2000. That study found 70 people classified as having CFS, and in 2002 and 2003, they were invited to take part in exhaustive two-day clinical and genetic evaluations.

The researchers also included 55 matched controls for the 58 CFS patients who agreed to take part, as well as 59 people with fatigue symptoms who did not meet the full CFS criteria (dubbed ISF). Also, they included 55 people with either ISF or CFS and concurrent melancholic depression.

The data gathered from the 227 participants, at a cost of about $2 million, included a full clinical evaluation, electrophysiologic measurements of sleep physiology, cognitive function, autonomic nervous system function, and detailed blood work that included DNA and gene activity analysis, Dr. Reeves said.

The next step was to share the data with four teams of researchers, which each took a different approach to the analysis, said molecular epidemiologist Suzanne Vernon, Ph.D., of the CDC's CFS Research Laboratory.

For the genetic analysis, she said, "we took a pathway-specific approach. We targeted about 50 genes and 500 polymorphisms in genes that are active in the hypothalamus-pituitary-adrenal (HPA) axis."

It turned out that all four groups zeroed in on five single nucleotide polymorphisms (SNPs) in three genes - those coding for the glucocorticoid receptor, for serotonin, and for tryptophan hydroxylase - which, she said, "are very important in the function of the HPA, which is the body's stress response system."

The effect of the variations, Dr. Reeves said, appears to be that people with them are less able to cope with stress.

One of the research groups, he said, identified three distinct fatigued groups - those with extreme fatigue, those with symptoms such as heart-rate variability and cortisol disturbances, and a group that was primarily menopausal women.

"The genes that Dr. Vernon mentioned distinguished the three fatigue groups from those that were not fatigued and two of those genes distinguished between the fatigue groups," Dr. Reeves said.

A study such as the one in Wichita produces enormous amounts of data, which must be reconciled if useful conclusions are to be drawn, said Jan Witkowski, Ph.D., director of the Banbury Center at the Cold Spring Harbor (N.Y.) Laboratory. The 14 research papers "are a heroic attempt to do so," he said in an accompanying editorial.

But while the amounts of data are large, Dr. Witkowski added, other disciplines have overcome greater challenges and "there is every reason to believe that continuing technical and intellectual advances" will help clarify the basis of diseases such as CFS.

What To Call It

Although there is agreement on the genuine threat to health, happiness, and productivity posed by CFS/ME, various physicians' groups, researchers, and patient activists champion very different ideas regarding diagnostic criteria and favored treatments, resulting in ongoing controversy about nearly all aspects of the disorder. The name chronic fatigue syndrome is itself controversial, with some patient advocates and other authorities preferring terms such as myalgic encephalomyelitis ("ME" or "CFS/ME") and post-viral fatigue syndrome ("PVFS"), which imply specific underlying etiologies or pathologic processes.

Yes, CFS/ME is Real

A lack of information and awareness has led to many patients being stigmatized as hypochondriac or lazy. The Centers for Disease Control & Prevention have now recognized CFS/ME as a serious illness and have recently launched a campaign to raise public and medical awareness about it. The American Medical Association (AMA), the World Health Organization (WHO), and the National Institutes of Health (NIH) are among those who have accepted CFS/ME as a legitimate physical illness and a major cause of disability.

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  • Michael Smith, Chronic Fatigue Syndrome Linked to Three Genes, Published: April 20, 2006, MedPage Today and Everyday Health, Inc., Accessed Aug. 1, 2012.

  • N. Sinaii, S.D. Cleary, M.L. Ballweg, L.K. Nieman and P. Stratton, High rates of autoimmune and endocrine disorders, fibromyalgia, chronic fatigue syndrome and atopic diseases among women with endometriosis: a survey analysis, Human Reproduction, Vol. 17, No. 10, 2715-2724, October 2002, Accessed Dec. 1, 2009.

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  • Whittemore Peterson Institute, Institute for Neuro-Immune Disease,, Accessed Nov. 1, 2009.

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  • Afari N, Buchwald D (2003). "Chronic fatigue syndrome: a review". Am J Psychiatr. PMID 12562565
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