Prion diseases: Kuru and Creutzfeldt-Jakob syndrome
Causes, Symptoms, and Treatment (Genetics & Inherited Conditions)
Kuru and Creutzfeldt-Jakob syndrome, degenerative diseases of the human central nervous system, are among a group of diseases that also affect cattle (mad cow disease) and sheep (scrapie). They have been classified in several ways, including “slow-virus” infections (because of the extremely long incubation period between contact and illness) and “spongiform encephalopathies” (because of the large holes seen in the brain after death). However, a virus that may cause such a disease has never been found, and the body does not respond to the disease as an infection. The only clue to the cause is the accumulation of a transmissible, toxic protein known as a prion; therefore, these disorders are now known simply as “prion diseases.”
Creutzfeldt-Jakob syndrome is rare: Approximately 250 people die from it yearly in the United States. It usually begins in middle age with symptoms that include rapidly progressing dementia, jerking spastic movements, and visual problems. Within one year after the symptoms begin, the patient is comatose and paralyzed, and powerful seizures affect the entire body. Death occurs shortly thereafter. The initial symptom of the illness (rapid mental deterioration) is similar to other disorders; therefore, diagnosis is difficult. No typical infectious agent (bacteria or viruses) can be found in the blood or in the fluid that surrounds the brain and spinal cord. X rays and other...
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Properties of Prions (Genetics & Inherited Conditions)
Most of the research on prion diseases has focused on scrapie in sheep. It became clear that the infectious particle had novel properties: It was not a virus as had been suspected, nor did the body react to it as an invader. It was discovered that this transmissible agent was an abnormal version of a common protein, which defied medical understanding. This protein is normally secreted by nerve cells and is found on their outer membranes. Its gene is on chromosome 20 in humans. The transmissible, infectious fragment of the prion somehow disrupts the nerve cell, causing it to produce the abnormal fragment instead of the normal protein. This product accumulates to toxic levels in the tissue and fluid of the brain and spinal cord over many years, finally destroying the central nervous system.
Prion infection appears to occur from exposure to infected tissues or fluids. Transmission has occurred accidentally through nerve tissue transplants and neurosurgical instruments. Prions are not affected by standard sterilization techniques; prevention requires careful handling of infected materials and extended autoclaving of surgical instruments (for at least one hour) or thorough rinsing in chlorine bleach. The agent is not spread by casual contact or air, and isolating the patient is not necessary.
Other human degenerative nervous system diseases whose causes remain unclear also show accumulations of proteins to toxic...
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Further Reading (Genetics & Inherited Conditions)
Aguzzi, Adriano, and Charles Weismann. “Prion Research: The Next Frontiers.” Nature 389, no. 6653 (October 23, 1997): 796. An overview of the history of research into prions and prion diseases.
Baker, Harry F., ed. Molecular Pathology of the Prions. Totowa, N.J.: Humana Press, 2001. Overview of research on prion diseases. Illustrated, bibliography, index.
Goldman, Lee, and Dennis Ausiello, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia: Saunders Elsevier, 2008. A classic medical reference text that covers prion diseases. Bibliography, index.
Groschup, Martin H., and Hans A. Kretzschmar, eds. Prion Diseases: Diagnosis and Pathogenesis. New York: Springer, 2000. Comprehensive collection of research articles on the pathogenesis of prion diseases in humans and other animals, pharmacology, epidemiology, and diagnosis. Illustrations (some color), bibliography.
Harris, David A., ed. Prions: Molecular and Cellular Biology. Portland, Oreg.: Horizon Scientific Press, 1999. Focuses on the cellular, biochemical, and genetic aspects of prion diseases. Illustrations, bibliography, index.
Klitzman, Robert. The Trembling Mountain: A Personal Account of Kuru, Cannibals, and Mad Cow Disease. New York: Plenum Trade, 1998. Autobiographical account of a study of kuru disease in Papua New Guinea. Illustrations, index.
Max, D. T. The Family That...
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Web Sites of Interest (Genetics & Inherited Conditions)
Genetics Home Reference, Prion Disease. http://ghr.nlm.nih.gov/condition=priondisease. Describes the genes related to prion disease and offers links to additional sources of information.
Medline Plus, Creutzfeldt-Jakob Disease. http://www.nlm.nih.gov/medlineplus/creutzfeldtjakobdisease.html. This page in the site created by the U.S. National Library of Medicine and the National Institutes of Health provides numerous links to information about Creutzfeldt-Jakob disease.
National Institute of Neurological Disorders and Stroke, NINDS Kuru Information Page. http://www.ninds.nih.gov/disorders/kuru/kuru.htm. Offers a brief overview of the disease and links to additional information about kuru and other prion diseases.
National Organization for Rare Disorders. http://www.rarediseases.org. Searchable site by type of disorder. Includes background information on Creutzfeldt-Jakob syndrome, a list of other names for the disorder, and a list of related organizations.
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