The patient with the shortest disease duration (27 months) carried a Y226X mutation and showed PrP-CAA without any neurofibrillary lesions, whereas the patient with the longest disease duration (72 months) had a Q227X mutation and showed an unusual Gerstmann-Sträussler-Scheinker disease phenotype with numerous cerebral multicentric amyloid plaques and severe neurofibrillary lesions without PrP-CAA.
GSS and PrP-CAA are associated with point mutations of the prion protein gene (PRNP); these conditions show a broad spectrum of clinical presentation, the main signs being ataxia, spastic paraparesis, extrapyramidal signs and dementia.