Chronic Fatigue Syndrome: Gene Link?

[GUNNER]

A study published Wednesday shows evidence of the genetic underpinnings of aspects of chronic fatigue syndromechronic fatigue syndrome (CFS), a disorder affecting up to 1 million Americans.

CDC researchers say they've uncovered genetic evidence linking symptoms of the disease -- including fatigue, chronic pain, and memory problems -- with genetic factors governing how the body handles stress.

Specifically, the researchers say they've found evidence that people with CFS symptoms have genetic factors that could alter how those people react to stress from life events, injury, or infections over the course of their lives, potentially giving rise to the disorder's unpleasant symptoms.

The research, which has yet to be replicated, is a first step toward improving diagnosis of chronic fatigue syndrome or targeting treatments to specific aspects of the disease, the scientists said.

Syndrome's Biological Basis

"It really is the first credible evidence of a biological basis for chronic fatigue syndrome," CDC director Julie M. Gerberding, MD, told reporters on a telephone conference call.

To do the study, published in the April issue of the journal Pharmacogenomics, CDC researchers closely analyzed data from 277 adults from Wichita, Kan. The participants included people with chronic fatigue and also nonfatigued people for comparison. Subjects were put through a battery of lab tests, psychiatric tests, and mental function tests, including screens of pain thresholds, memory functioning, sleep quality, and stress responses. Approximately 20,000 genetic factors were also analyzed.

The information was then shared with 20 different researchers working together in teams, who were allowed to analyze and interpret the data looking for possible biological explanations for chronic fatigue syndrome.

CDC researcher Suzanne D. Vernon, said that different labs came up with genetic results pointing to a "clear biologic basis for CFS.

"Now what we've done is create a molecular profile of individuals" with chronic fatigue, Vernon said.

Looking to the Future

Despite the findings, the study leaves several unanswered questions. First, researchers were not able to determine how strongly each of the genetic factors influences chronic fatigue symptoms or whether people unaffected by chronic fatigue may have the same genetic factors present.

Second, scientists still will have trouble defining exactly how gene profiles may point to someone with chronic fatigue, a disorder that is diagnosed by symptoms, not by a particular alteration in the body or special blood tests.

Still, Vernon said the results could help drug developers target medications toward specific physiologic problems involved in chronic fatigue. It could also help doctors decide what kind of treatment might benefit a patient based in part on genetic testing.

CDC scientist William Reeves said the agency has already begun an attempt to repeat the findings in another patient population in Georgia.

Now the question is, "can we replicate it in a completely independent sample," he said.