Classic CJD (Creutzfeldt-Jakob Disease)

Also known as Classic CJD, Creutzfeldt-Jakob Disease is what is called a human prion disease. Classic CJD is characterized as a neurodegenerative disorder. It is a fast acting disease and results in death typically a year after the initial infection.

It is important to note that Classic CJD is not related to Variant CJD, which is an altogether different prion disease that is related to mad cow disease, also known as BSE. Classic CJD is not in any way related to BSE.

First diagnosed in the 1920s, Classic CJD tends to strike suddenly and randomly as normal prion proteins transform into abnormal prions. Classic CJD is found all over the world. In America, there is about one to two cases out of a million people each year. Individuals over fifty years old are at greater risk, and the average rate for that target population is nearly four cases out of a million each year. There are approximately three hundred cases in total of Classic CJD in the United States per year.

Approximately fifteen percent of Classic CJD cases are caused by inherited mutations of prion proteins rather than a sudden and random occurrence. The inherited forms of Classic CJD include diseases such as Fatal Familial Insomnia and Gerstmann Straussler Scheinker Syndrome.

There are ways to distinguish Classic CJD from Variant CJD by examining their respective pathologic as well as clinical characteristics. The median age at death for Classic CJD is 68 years old, while the median age at death for Variant CJD is significantly lower at 28 of age. Variant CJD has a much longer median duration of illness at approximately 14 months while Classic CJD has a median duration of about 5 months.

Clinical symptoms of Classic CJD include dementia and early neurological signs. Meanwhile, the signs of Variant CJD include delayed neurological signs, distinguished psychiatric symptoms, and painful dyesthesiasis. When using an electroencephalogram, periodic sharp waves are often present in Classic CJD, while the opposite is true for Variant CJD. Pulvinar signs are not reported for Classic CJD on MRIs while they are present for over three quarters of Variant CJD cases.

Florid plaques on neuropathology are very rare and usually absent from Classic CJD, while they are quite common and in abundance for Variant CJD. Immunohitochemical analysis of brain tissue shows variable accumulation for Classic CJD while Variant CJD displays marked accumulation of the protease-resistance prion protein. Variant CJD shows a marked accumulation of the protease-resistance prion protein again when an immunoblot analysis with an increased glycoform ratio is performed. Meanwhile, such is not reported for Classic CJD. The presence of an agent in lymphoid tissue is not easily detectable in cases of Classic CJD while the opposite is true for Variant CJD.

The contrasting clinical and pathological traits of Classic CJD and Variant CJD have been reported from E. Belay’s study entitled “Schonberger L. Variant Creutzfeldt-Jakob Disease and Bovine Spongiform Encephalopathy.” It can be found in the volume 22 of Clinical Lab Medicine published in 2002.