Background: We evaluated the features of neuropathology, abnormal prion protein (PrP) molecules, and clinical data of a Chinese woman diagnosed with familiar Creutzfeldt-Jakob disease (CJD), having 7 octa-repeats inserted with codon 129 methionine homozygote in the PRNP gene.
Methods: Neuropathologic characteristics of the brain were analyzed by hemotoxylin-eosin stain and electronic microscopy. The presence of abnormal PrP in brains was detected by proteinase K and PrP molecules were evaluated by deglycosylation assay.
Results: Spongiform degeneration, with diffuse neuronal loss and mild astrocytic gliosis, as well as with profound degeneration of neurons and astrocytes was observed. Proteinase K-resistant PrP was deposited widely in various regions of the brain. Calculation of the glycosylation ratios of proteinase K-resistant PrP molecules identified that the monoglycosyl isomer was predominant. PrP deglycosylation tests allowed for the identification of a predominant 19-kDa PrP signal that represents a partially proteolytic C-terminal segment, a 27-kDa band that represents the full-length wild-type PrP molecule, and a 30-kDa band that probably corresponds to the full-length mutant PrP molecule.
Conclusion: Sporadic CJD-like neuropathologic changes and deposits of proteinase K-resistant PrP have been identified in this familiar CJD case with a 168 base pair nucleotide insertion. The clinical features differ from previously reported cases that had 7 octa-repeat insertion, but bear similarities to sporadic CJD.