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Scientists at The Scripps Research Institute Study the Role of Genetics in Narcolepsy

La Jolla, CA. August 24, 1999 -- Scientists at The Scripps Research Institute (TSRI) and their colleagues at several other medical research institutions have received grant funding from the National Institutes of Health to study the genetic basis for narcolepsy, a potentially disabling, life-long condition estimated to afflict about one in every 1,000 people in this country.

According to the study's lead investigator, Merrill M. Mitler, Ph.D., Professor, Department of Neuropharmacology, "Narcolepsy represents a significant health problem in the United States and throughout the world. People with the disease are disabled, and often in a quandary about major life issues, including whether to have children, and how to determine which occupations are safe and appropriate. In addition, from a public policy and scientific point of view, interest in the etiology of narcolepsy is high, since sleep and wakefulness have a dramatic impact on many areas of modern society, such as transportation, industrial safety and overall productivity."

This study, "Narcolepsy: Multi-Center Genetic and Family Study" will estimate the rate at which narcolepsy runs in families. Its goal is to identify a gene or a cluster of genes associated with the transmission of the disease.

While the inheritance of narcolepsy is not known, it is strongly but not always associated with a gene that gives rise to a particular antigen, known as human leukocyte antigen, or HLA. A person with this antigen is probably more susceptible to narcolepsy, according to Mitler. That being the case, however, persons in families with well-diagnosed narcolepsy generally do not have this genetic marker. So the presence of HLA-associated and non-HLA associated forms of narcolepsy indicates that it is at least two distinct disorders, he continued.

Another development in the field is the recent recognition of the connection between sleep and hypothalamic peptides, known as hypocretins. Defects in the genes related to the hypocretin system have been linked to narcolepsy in animals. Since they are highly conserved across many mammals, including humans, the researchers will evaluate these genes in families of patients with narcolepsy.

"Through sophisticated genetic analyses, including DNA testing and fingerprinting, we hope to determine why the non-familial form of narcolepsy is so strongly associated with human leukocyte antigen. The use of a case series approach will allow us to estimate the population rates of the transmission of narcolepsy from one family member to another," said Mitler.

Co-investigators of the study include Roza Hayduk, M.D., Laboratory for Sleep, Fatigue and Safety, The Scripps Research Institute; M. Anne Spence, Ph.D., Department of Pediatrics, University of California, Irvine Medical Center; Pam Flodman, PhD., Department of Pediatrics, University of California, Irvine Medical Center; L. Leigh Field, Ph.D., Department of Medical Genetics, University of Calgary, Alberta, Canada; and Clyde Dos Santos, M.D., WestMed Sleep Disorders Center, Anaheim.

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