Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD) is a rare, fatal, neurodegenerative disease. It is a type of subacute spongiform encephalopathy caused by prion proteins. These proteins induce the formation of amyloid folds resulting in tightly packed beta-pleated sheets resistant to proteases.

Features

• dementia (rapid onset)
• myoclonus
• rigidity

Investigation

• CSF is usually normal
• EEG: biphasic, high amplitude sharp waves (only in sporadic CJD)
• MRI: hyperintense signals in the basal ganglia and thalamus

Sporadic CJD

• accounts for 85% of cases
• 10-15% of cases are familial
• mean age of onset is 65 years

New variant CJD

• younger patients (average age of onset = 25 years)
• psychological symptoms such as anxiety, withdrawal and dysphonia are the most common presenting features
• the 'prion protein' is encoded on chromosome 20 - it's role is not yet understood
• methionine homozygosity at codon 129 of the prion protein is a risk factor for developing CJD - all patients who have so far died have had this
• median survival = 13 months