• What is CJD?
• What are the biochemical features of CJD?
• Creutzfeldt-Jakob Disease At A Glance

What is CJD?

Creutzfeldt-Jakob disease (CJD) is the dementing form of the human prion diseases (also known as spongiform transmissible encephalopathies or infectious amyloidoses). A prion is an unconventional, transmissible agent (not a virus or a bacterium). Prions are special proteins that can be transmitted from animal to animal to cause a group of degenerative diseases of the nervous system. These diseases can be manifest as sporadic, infectious, or inherited disorders.

CJD is characterized by forgetfulness and nervousness; jerky, trembling hand movements; unsteady gait; myoclonus; chronic dementia; severe balance disturbance; and muscular rigidity. Patients can have characteristic brain electrical changes referred to as periodic electroencephalogram (EEG) complexes. Brain biopsy (pathology under the microscope) includes typical tissue changes referred to as status spongiosus, diffuse nerve cell degeneration, and glial proliferation. There is no known treatment or cure for CJD. Bovine spongiform encephalopathy (BSE) represents another, similar disease of cattle.

About 15% of cases of CJD have a family history that demonstrates an inherited form of the illness (autosomal dominant transmission). Onset of disease is significantly earlier in familial cases. Temporal and spatial separations between affected relatives suggested that incubation periods range at least from 1 to 4 decades. Affected sibs tend to die at the same age and not at the same time. The mean age of onset is 61.5 years, and 90 % of patients die within a year of onset.

Creutzfeldt-Jakob disease occurs in unusually high frequency in Chile. In Israel, the mean annual incidence rate per million population was 43 among Libyan-born Jews and 0.9 in the rest of the population. Patients have been described with disease believed to be transmitted from infected tissues, such as cornea.

What are the biochemical features of CJD?

Bockman et al. (1985) found that purified fractions from the brains of 2 patients with CJD contained special proteins (protease-resistant proteins). These proteins reacted with antibodies raised against the scrapie prion protein PrP 27-30. Rod-shaped particles found in the brain tissue of the patients were similar to those from rodents with either scrapie or experimental CJD.

Based on these and additional studies, it was concluded that prion protein is necessary for normal transmission of electrical impulses between nerves (synaptic function). It was theorized that inherited prion disease may result from a dominant negative effect with generation of PrP-Sc, an abnormal prion. The modified form of cellular PrP ultimately leads to progressive loss of functional PrP (PrP-C). For further information on prion function see this reference.

Creutzfeldt-Jakob Disease At A Glance

• CJD a dementing disease of the brain caused by an unconventional, transmissible agent (prion).
• Symptoms of CJD include forgetfulness, nervousness, jerky trembling hand movements, unsteady gait, muscle spasms, chronic dementia, balance disorder, and loss of facial expression.
• Most cases occur randomly (sporadic), but inherited forms exist.
• There is neither treatment nor cure for CJD.

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