About CJD and Prion Disease
Prion diseases are a group of rare, invariably fatal brain disorders which occur both in humans and certain animals.
In humans the best known of the prion diseases is Creutzfeldt-Jakob Disease (CJD), which reportedly affects around one person per million per population per year. In the United States this translates to approximately 320 new cases per year. It is well known that CJD is very difficult to diagnose leading to speculation that the one case per million report may be incorrect. Most of the cases are "sporadic" CJD (sCJD), occurring for no known reason. The sporadic form accounts for approximately 85% of the cases, and the familial form approximately 10% to 15%. There have also been a few cases that have occurred from contamination via medical procedures; this type is known as iatrogenic or Acquired CJD. In the 1980s and 1990s, another type of Acquired CJD called variant (vCJD) was identified in young people. CJD has been linked to ingestion of beef tainted with BSE (bovine spongiform encephalopathy), most cases have occurred in, or been tied to food from, the United Kingdom.
In animals, prion diseases first came to public attention in the mid 1980s in the form of the BSE epidemic in the United Kingdom. BSE (bovine spongiform encephalopathy) is a prion disease in cattle. Tissue from infected animals may have contaminated cattle feed, leading to the silent spread of the BSE epidemic. There is also a theory that BSE came from feed contaminated with scrapie, the long established sheep prion disease. Inevitably, concern over whether BSE could pass to humans mounted.
For information on the forms of CJD, click the links below:
Glossary of Terms
14-3-3: Detection of elevated levels of the 14-3-3 protein in the cerebrospinal fluid (CSF) may support a CJD diagnosis in appropriate context.
Akinetic mutism: A state where a person can no longer move or talk due to damage to the brain, but the person is awake (not comatose) and their eyes are open and can follow what is going on around them.
Aphasia: A loss of the ability to produce and/or understand language due to injury to the brain.
Apraxia: The loss of the ability to perform tasks that require remembering patterns or sequences of movements (like waving goodbye).
Ataxia: Wobbliness, unsteady walk and clumsiness usually caused by damage to the cerebellum, a part of the brain which controls balance and coordination.
Atrophy: Wasting away or shrinking. Neuronal atrophy is wasting away of neurons, a decrease in neuronal density.
Autopsy: An examination of the brain after death.
Autosomal dominant: Individuals with autosomal dominant diseases have a 50-50 chance of passing the mutated gene on to each of their children.
Bovine Spongiform Encephalopathy (BSE): A prion disease found in cows, also known as "mad cow disease."
Brain biopsy: A brain biopsy is a surgical procedure on a live patient to remove a small specimen of tissue from the brain. Because the specimen may be taken from a non-affected part of the brain and result in a false negative, a brain biopsy should only be performed if other conditions besides CJD are suspected.
Cerebrospinal fluid (CSF): A clear, watery liquid that bathes, cushions and protects the brain and spinal cord.
Chronic wasting disease (CWD): A prion disease of elk and deer.
Creutzfeldt-Jakob disease (CJD): Creutzfeldt-Jakob disease is a rare, degenerative, invariably fatal brain disorder. Typically, onset of symptoms occurs at about age 60. There are three major categories of CJD: sporadic CJD, genetic CJD and acquired CJD. The first concern is to rule out treatable forms of dementia, such as encephalitis or chronic meningitis. Other tests may support the diagnosis (14-3-3/Tau/RT-QuIC; CSF, EEG and brain MRI.) The only way to confirm a diagnosis of CJD is by neuropathologic examination.
Dementia: A deterioration of intellectual faculties, such as memory, concentration and judgment, that affects daily functioning. It is sometimes accompanied by emotional disturbance and personality changes.
Diffusion Weighted MRI: An MRI imaging technique that can be used to help diagnose CJD.
Dysphagia: Difficulty in swallowing due to problems in nerve or muscle control.
Dystonia: Involuntary, sustained muscle contractions that frequently cause twisting body motions, tremor, and abnormal posture (these movements may involve the entire body, or only an isolated area).
Electroencephalogram (EEG): Flat metal discs (electrodes) placed on your scalp detect and record the patterns of electrical activity generated by your brain.
Encephalopathy: Any disease in which the functioning of the brain is affected.
Familial Prion Diseases: There are three distinct familial prion diseases: Familial Creutzfeldt-Jakob Disease (fCJD), Fatal Familial Insomnia (FFI) and Gerstmann-Sträussler-Scheinker disease (GSS). Familial prion diseases are defined by the presence of a mutation in the PRNP gene. Familial prion diseases account for approximately 10 to 15 percent of all human prion diseases.
Fatal familial insomnia (FFI): Fatal familial insomnia (FFI) is a very rare autosomal dominant inherited prion disease.
Gait: How a person walks.
Gerstmann-Sträussler-Scheinker Syndrome (GSS): Gerstmann-Sträussler-Scheinker disease (GSS) is a very rare, neurodegenerative brain disease. Onset of the disease usually occurs between the ages of 35 and 55. In the early stages, patients may experience varying levels of ataxia (lack of muscle coordination), including clumsiness, unsteadiness, and difficulty walking. As the disease progresses, the ataxia becomes more pronounced and most patients develop dementia.
Human prion disease: Prion diseases or transmissible spongiform encephalopathies (TSEs) are a family of rare progressive neurodegenerative disorders that affect both humans and animals. They are characterized by a spongy appearance of the brain and accumulation of abnormal prion proteins.
Iatrogenic (iCJD): is due to transmission of prion disease through specific medical procedures like human growth hormone and corneal and dura mater transplants obtained from cadavers affected by prion disease.
MRI (magnetic resonance imaging): A radiology technique that uses magnetism, radio waves and a computer to produce non-invasive, high quality images of internal structures of the body. An MRI is painless, does not use x-ray radiation and is a powerful tool for delineating brain structure.
Mutation: A permanent change in the DNA or RNA - the molecular "blueprints" that direct the building of proteins. Mutations can be helpful, neutral or harmful and can be caused randomly or by environmental factors.
Myoclonus: Sudden, involuntary jerking or twitching of a muscle or group of muscles.
Polymorphism: A non-disease-causing variation in a certain gene that occurs in the normal population (e.g., codon 129 of the prion protein gene).
Prions: Transmissible proteins that cause prion diseases.
Pulvinar sign: Symmetrically increased signal intensity in the pulvinar region (posterior part of the thalamus) relative to the signal intensity in other deep and cortical gray matter areas on an MRI; the presence of this MRI feature may suggest a vCJD diagnosis in the appropriate clinical context.
Real-Time Quaking Induced Conversion (RT-QuIC): RT-QuIC can detect the actual abnormal prion protein and is 98.5% diagnostic of prion disease should it be detected in the spinal fluid.
Scrapie: A prion disease in sheep and goats.
Spinal Tap: A doctor collects the cerebrospinal fluid (CSF) by doing a lumbar puncture (spinal tap) in which a very thin needle is gently inserted in the lower back between two vertebrae, the bony structures that make up the spine. It is used to look for infections, inflammation, and markers that may suggest prion disease (14-3-3/Tau/RT-QuIC.)
Sporadic CJD: The cause of "classic" or "sporadic" CJD is unknown, which means it occurs in people without any known risk factors or gene mutations. Typical symptoms include imbalance and incoordination, memory loss and impaired thinking, and psychiatric symptoms such as anxiety or depression. Once the symptoms do appear, CJD typically progresses very quickly and is usually fatal within a few months of symptom onset. sCJD typically affects people in their 60s or later and is rarely seen in people younger than 40 years old. Sporadic CJD is the most common form of prion disease (85 percent.)
Strain: Types of prion proteins that demonstrate common illness characteristics (e.g., similar neuropathology, clinical symptoms, duration) in animals or humans (e.g., variant CJD, classical bovine spongiform encephalopathy)
Tau: A protein in the body that aids in the cellular structure (cytoskeleton) and cellular transportation. Elevated levels in CSF may be suggestive of prion disease.
Transmissible Spongiform Encephalopathy (TSE): A family of rare progressive neurodegenerative disorders that affect both humans and animals and are caused by prions (e.g., prion diseases.)
Variant CJD (vCJD): is a very rare form of prion disease caused by the ingestion of food contaminated with bovine spongiform encephalopathy (BSE). The vast majority of these cases have occurred in European countries, where the BSE epidemic occurred. There have been no documented cases of vCJD associated directly with beef consumption in the United States.
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