title: Prion protein amyloidosis with divergent phenotype associated with two novel nonsense mutations in PRNP.
abstract: Stop codon mutations in the gene encoding the prion protein (PRNP) are very rare and have thus far only been described in two patients with prion protein cerebral amyloid angiopathy (PrP-CAA). In this report, we describe the clinical, histopathological and pathological prion protein (PrP(Sc)) characteristics of two Dutch patients carrying novel adjacent stop codon mutations in the C-terminal part of PRNP, resulting in either case in hereditary prion protein amyloidoses, but with strikingly different clinicopathological phenotypes. 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. Western blot analysis in the patient with the Q227X mutation demonstrated the presence of a 7 kDa unglycosylated PrP(Sc) fragment truncated at both the N- and C-terminal ends. Our observations expand the spectrum of clinicopathological phenotypes associated with PRNP mutations and show that a single tyrosine residue difference in the PrP C-terminus may significantly affect the site of amyloid deposition and the overall phenotypic expression of the prion disease. Furthermore, it confirms that the absence of the glycosylphosphatidylinositol anchor in PrP predisposes to amyloid plaque formation.
authors.affiliation: Dutch Surveillance Centre for Prion Diseases, University Medical Centre Utrecht, 3584 CX Utrecht, The Netherlands. c.jansen@umcutrecht.nl
authors.forename: Casper
authors.initials: C
authors.lastname: Jansen
authors.forename: Piero
authors.initials: P
authors.lastname: Parchi
authors.forename: Sabina
authors.initials: S
authors.lastname: Capellari
authors.forename: Ad J
authors.initials: AJ
authors.lastname: Vermeij
authors.forename: Patrizia
authors.initials: P
authors.lastname: Corrado
authors.forename: Frank
authors.initials: F
authors.lastname: Baas
authors.forename: Rosaria
authors.initials: R
authors.lastname: Strammiello
authors.forename: Willem A
authors.initials: WA
authors.lastname: van Gool
authors.forename: John C
authors.initials: JC
authors.lastname: van Swieten
authors.forename: Annemieke J M
authors.initials: AJ
authors.lastname: Rozemuller
mesh_terms: D000328:Adult; D001483:Base Sequence; D015153:Blotting, Western; D001921:Brain / Q000473:pathology*; D028243:Cerebral Amyloid Angiopathy, Familial / Q000235:genetics* / Q000473:pathology; D018389:Codon, Nonsense; D005260:Female; D016098:Gerstmann-Straussler-Scheinker Disease / Q000235:genetics* / Q000473:pathology; D006801:Humans; D008875:Middle Aged; D010641:Phenotype; D018620:PrPSc Proteins / Q000235:genetics*; D000072002:Prion Proteins; D011328:Prions / Q000235:genetics*
chemical_list: D018389:Codon, Nonsense; C512656:PRNP protein, human; D018620:PrPSc Proteins; D000072002:Prion Proteins; D011328:Prions