PROTEIN AMYLOIDOSIS ASSOCIATED WITH A NOVEL STOP CODON MUTATION IN PRNP

We have characterized the clinicopathological and PrPSc phenotype of a patient carrying a novel stop codon mutation at codon 227, in the C-terminal part of the prion protein gene (PRNP), resulting in a C-terminally truncated protein lacking the glycosylphosphatidylinositol membrane anchor. A42 year old woman was evaluated for a slowly progressive hypokinetic rigid syndrome with cognitive decline. She was clinically diagnosed with frontotemporal dementia and died after a disease duration of 6 years. Neuropathological examination demonstrated a Gerstmann-Sträussler- Scheinker disease phenotype with multicentric amyloid plaques and neurofibrillary lesions in the cerebral grey matter but with relative sparing of the cerebellum.Western blot demonstrated the presence of an unglycosylated PrPSc fragment of about 7 kDa truncated at both the N- and C-terminal ends. This is the third stop PRNP mutation reported to date and the first not associated to a PrP-cerebral amyloid angiopathy.