A PRION DISEASE WITH A NOVEL 96-BASE PAIR INSERTIONAL MUTATION IN THEPRION PROTEIN GENE

There are coding mutations in the prion protein gene in familial Creut zfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker disease, an d other phenotypes that make up the inherited prion diseases. Insertio nal mutations consisting of two, five, six, seven, eight, and nine add itional octapeptide repeat elements are seen in the inherited prion di seases and usually present as atypical dementias with considerable int rafamilial phenotypic variability. A four-octarepeat insertion was rep orted previously in an individual without neurodegenerative disease wh o died of hepatic cirrhosis. Here we report a novel four-octarepeat in sertional mutation in a case with classical clinical, electroencephalo graphic and histopathologic features of CJD with the unusual finding o f pronounced prion protein immunoreactivity of the molecular layer of the cerebellum.