Causes of Creutzfeldt-Jakob Disease


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Cause statistics for Creutzfeldt-Jakob Disease: The following are statistics from various sources about the causes of Creutzfeldt-Jakob Disease:

  • 27 out of 7,700 people who received human growth hormone between 1963 and 1985 have since been diagnosed with Creutzfeldt-Jakob Disease in the US (NIDDK, NIH, 2002)
  • 89 out of 1,700 people who received human growth hormone between 1963 and 1985 have since been diagnosed with Creutzfeldt-Jakob Disease in France (NIDDK, NIH, 2002)
  • 38 out of 1,848 people who received human growth hormone between 1963 and 1985 have since been diagnosed with Creutzfeldt-Jakob Disease in England (NIDDK, NIH, 2002)
  • 5 people who received human growth hormone between 1963 and 1985 have since been diagnosed with Creutzfeldt-Jakob Disease in New Zealand (NIDDK, NIH, 2002)
  • 2 people who received human growth hormone between 1963 and 1985 have since been diagnosed with Creutzfeldt-Jakob Disease in Holland (NIDDK, NIH, 2002)
  • 1 people who received human growth hormone between 1963 and 1985 have since been diagnosed with Creutzfeldt-Jakob Disease in Brazil (NIDDK, NIH, 2002)
  • 1 people who received human growth hormone between 1963 and 1985 have since been diagnosed with Creutzfeldt-Jakob Disease in Australia (NIDDK, NIH, 2002)
  • 1 in 300 people who received human growth hormone have since been diagnosed with Creutzfeldt-Jakob Disease in England (NIDDK, NIH, 2002)
  • 1 in 104 people who received human growth hormone before 1977 have since been diagnosed with Creutzfeldt-Jakob Disease in England (NIDDK, NIH, 2002)

Cause details for Creutzfeldt-Jakob Disease: Some researchers believe an unusual "slow virus" or another organism causes CJD. However, they have never been able to isolate a virus or other organism in people with the disease. Furthermore, the agent that causes CJD has several characteristics that are unusual for known organisms such as viruses and bacteria. It is difficult to kill, it does not appear to contain any genetic information in the form of nucleic acids (DNA or RNA), and it usually has a long incubation period before symptoms appear. In some cases, the incubation period may be as long as 40 years. The leading scientific theory at this time maintains that CJD and the other TSEs are caused not by an organism but by a type of protein called a prion.

Prions occur in both a normal form, which is a harmless protein found in the body's cells; and in an infectious form, which causes disease. The harmless and infectious forms of the prion protein are nearly identical, but the infectious form takes a different folded shape than the normal protein. Sporadic CJD may develop because some of a person's normal prions spontaneously change into the infectious form of the protein and then alter the prions in other cells in a chain reaction.

Once they appear, abnormal prion proteins stick together and form fibers and/or clumps called plaques that can be seen with powerful microscopes. Fibers and plaques may start to accumulate years before symptoms of CJD begin to appear. It is still unclear what role these abnormalities play in the disease or how they might affect symptoms.

About 5 to 10 percent of all CJD cases are inherited. These cases arise from a mutation, or change, in the gene that controls formation of the normal prion protein. While prions themselves do not contain genetic information and do not require genes to reproduce themselves, infectious prions can arise if a mutation occurs in the gene for the body's normal prions. If the prion gene is altered in a person's sperm or egg cells, the mutation can be transmitted to the person's offspring. Several different mutations in the prion gene have been identified. The particular mutation found in each family affects how frequently the disease appears and what symptoms are most noticeable. However, not all people with mutations in the prion gene develop CJD. This suggests that the mutations merely increase susceptibility to CJD and that other, still-unknown factors also play a role in the disease. 1

From 10 to 15 percent of CJD cases are inherited, but cases have been associated with the use of contaminated corneal transplants, electrode implants, dura mater grafts, and receipt of human growth hormone. 2

Scientists don't fully understand what causes CJD. Evidence suggests that a unique infectious agent called a prion [pree'-on] may be responsible. Unlike viruses, bacteria, and other infectious agents that contain genetic material, prions consist of protein without any genetic material. 3

Causes of Creutzfeldt-Jakob Disease: medical news summaries: The following medical news items are relevant to causes of Creutzfeldt-Jakob Disease:

Related information for causes of Creutzfeldt-Jakob Disease: Further relevant information on causes of Creutzfeldt-Jakob Disease may be found in the risk factors for Creutzfeldt-Jakob Disease and underlying causes of Creutzfeldt-Jakob Disease.

Footnotes:
1. excerpt from Creutzfeldt-Jakob Disease Fact Sheet: NINDS
2. excerpt from Facts About Creutzfeldt-Jakob Disease: CDC-OC
3. excerpt from Update Follow-Up Study of NHPP Growth Hormone Recipients: NIDDK

Last revision: May 26, 2003

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