Sporadic Creutzfeldt–Jakob Disease

Sporadic Creutzfeldt–Jakob disease is the most frequent human prion disease, with a yearly mortality of between one and two cases per million. It is usually assumed that it arises spontaneously, i.e. for no obvious cause. Neuropathological examination has remained the most important tool for a definite diagnosis. Most sCJD cases have characteristic clinical and neuropathological features that include spongiform change, neuronal loss, gliosis, and deposition of a disease‐associated form of the prion protein that can be demonstrated by specific methods in immunohistochemistry (specific pretreatment of paraffin sections is necessary) or immunoblotting (after digestion by proteinase). Despite these common features, there may be considerable clinicopathological heterogeneity according to a genetic polymorphism at the prion protein gene codon 129 and the type of protein‐resistant prion protein (type 1 or 2) present in the brain, defining distinct molecular subtypes; these subtypes may occur in pure or mixed forms.