A novel phenotype in familial Creutzfeldt-Jakob disease: Prion protein gene E200K mutation coupled with valine at codon 129 and type 2 protease-resistant prion protein

A novel phenotype of familial Creutzfeldt-Jakob disease (CJD) with mutated codon 200 of the prion protein gene (PRNP) coupled with the valine codon 12 9 (E200K-129V haplotype) has two features never observed in subjects carryi ng the pathogenic mutation coupled with the methionine codon 129 (E200K-129 M haplotype): (1) plaque-like prion protein (PrP) deposits in the cerebellu m and (2) type 2 protease-resistant prion protein (PrPres). This observatio n further underlines the role of codon 129 on the mutated PRNP allele in mo dulating the phenotype of familial prion diseases.