Creutzfeldt-Jakob disease (CJD) is the most common form of prion disease in humans. There are three forms: sporadic, in which the origin is unknown, hereditary, due to a mutation in the prion protein gene, and acquired, such as the variant form of Creutzfeldt-Jakob disease linked to the ingestion of bovine derivatives contaminated with an abnormal prion protein.
Symptoms of Prion Diseases
The symptoms of prion diseases are manifold. The main one is dementia, which is a rapid deterioration of cognitive functions such as memory and language, accompanied by various neurological symptoms such as myoclonus (muscle twitching), disturbances in balance, vision or coordination of movements. The disease may begin with sleep disturbances or anxiety before symptoms of dementia appear.
Sporadic Creutzfeldt-Jakob Disease (CJD)
The sporadic form of Creutzfeldt-Jakob disease (CJD) begins at an average age of 65. The disease progresses very quickly, causing death after an average of 6 months.
Genetic forms of prion diseases
Among the hereditary forms of prion diseases, there are three: genetic Creutzfeldt-Jakob disease, Gerstmann-Straussler-Scheinker syndrome (GSS), and Fatal Family Insomnia (FFI). All three are due to a different mutation in the same gene encoding the prion protein. The evolution of these forms varies greatly from a few months to a few years.
Symptoms can vary significantly from those described above. If the symptoms of CJD-genetics are close to the sporadic form, the Gerstmann-Straussler-Scheinker syndrome will be characterised rather by damage to the cerebellum with symptoms of ataxia, whereas the Fatal Family Insomnia is primarily a very severe and intractable sleep disorder, associated with disturbances of the vegetative system (day-night rhythm, sphincteric disorders, cardio-respiratory disorders, etc.).
Acquired forms of prion diseases
The acquired forms are perhaps the best known. In particular, the variant form of Creutzfeldt-Jakob disease. This form appeared in 1996 in the United Kingdom. It is linked to the ingestion of bovine derivatives contaminated with an abnormal prion protein responsible for bovine spongiform encephalopathy. It is best known as “mad cow disease”. Variant CJD occurs primarily in young adults (about 30 years of age) and begins with psychiatric symptoms such as anxiety or depression before neurological signs and later dementia appear. It progresses slightly more slowly than the sporadic form, over about 18 months.
There are other acquired forms of prion diseases such as iatrogenic Creutzfeldt-Jakob disease, which is transmitted by accident during a therapeutic procedure. This form was first revealed in the 1970s and 1980s with the origin of corneal or dura mater transplants or growth hormone treatments, produced at the time from the pituitary gland of deceased persons. The incubation period for this form is 10 to 15 years.
At Paris Brain Institute
Stéphane Haïk, team leader at Paris Brain Institute and also coordinator of the National Reference Centre for Prion Diseases, is working to develop diagnostic tests to detect Creutzfeldt-Jakob disease. His team has been involved in the development of a biological test that can detect the variant Creutzfeldt-Jakob Disease (vCJD) prion in blood.
