Prion protein amyloidosis with divergent phenotype associated with two novel nonsense mutations in PRNP

Acta Neuropathol. 2010 Feb;119(2):189-97. doi: 10.1007/s00401-009-0609-x. Epub 2009 Nov 13.

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.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Base Sequence
  • Blotting, Western
  • Brain / pathology*
  • Cerebral Amyloid Angiopathy, Familial / genetics*
  • Cerebral Amyloid Angiopathy, Familial / pathology
  • Codon, Nonsense
  • Female
  • Gerstmann-Straussler-Scheinker Disease / genetics*
  • Gerstmann-Straussler-Scheinker Disease / pathology
  • Humans
  • Middle Aged
  • Phenotype
  • PrPSc Proteins / genetics*
  • Prion Proteins
  • Prions / genetics*

Substances

  • Codon, Nonsense
  • PRNP protein, human
  • PrPSc Proteins
  • Prion Proteins
  • Prions