The findings were released yesterday in the April issue of the US scientific journal Pharmacogenomics.

    Chronic fatigue syndrome, commonly known as CFS, was first recognized in the 1980s but was long associated with "a bunch of hysterical, upper-class white women," said Dr. William C. Reeves, leading researcher of the Centers for Disease Control and Prevention (CDC). 

    Physiological manifestations of the disease can include sore throat, tender lymph nodes, headaches of a new or different type from those experienced in the past, and malaise after exertion. Such symptons must be present for at least six months for a diagnosis, according to researchers.

    The study has revealed that the disease CFS is caused by genetic mutations that impair the central nervous system's ability to adapt to stressful situations.

    Researchers at CDC identified 227 patients at Wichita, Kansas, who spent two full days in a hospital undergoing a series of blood tests, hormone studies, psychological exams and sleep studies.

    The CDC, which invested about $2 million in the testing, then made blood-test results and other data available to researchers, who performed a wide variety of analyses.

    The teams found that there were at least four distinct forms of the disease, each with its own genetic profile and symptoms but all including disabling fatigue.

    But all the forms shared genetic mutations ¡ª technically called single nucleotide polymorphisms ¡ª related to brain activity that mediated the response to stress.

    In particular, five polymorphisms in three genes were "very important," said Dr. Suzanne Vernon of the CDC, co-leader of the study. Those polymorphisms alone were sufficient to diagnose about 75% of cases.

    Dr. Reeves said the study demonstrated that people with chronic fatigue syndrome were unable to deal with everyday challenges and adversity, including injuries, illnesses, divorce and stressful jobs due to a genetic predisposition which reduces their ability to deal with physical and psychological stress.

    The research offers some of the first credible scientific evidence that genetics combined with stress can trigger chronic fatigue syndrome.

    It is estimated that the disease affects more than one million Americans, with women suffering at four times the rate of men, according to the disease control agency.

¡¡  Researchers said the findings could help lead to better means of diagnosing and treating chronic fatigue syndrome and predicting who is likely to develop the disorder.Enditem

    (Agencies)