E200K mutation of the prion protein gene (PRNP) presented with a variety of phenotypes. A 55-year-old woman complaining of slowly progressive walking difficulties came to our observation. She showed a severe progressive ataxo-spastic syndrome but a mild cognitive impairment only. Repeated EEGs showed a diffuse slowing of the rhythm without specificity. Brain MRI revealed by FLAIR showed widespread multiple hyperintensities in the whole cerebral cortex, caudate and putamen nuclei, and in the pulvinar and medial thalamus bilaterally. These signal abnormalities were best detected by DWI with restricted diffusion on ADC map. The clinical diagnosis of possible genetic Creutzfeldt-Jakob disease (CJD) has been confirmed by PRNP gene analysis which revealed the presence of a E200K mutation. This report confirms the heterogeneity of phenotypes in E200K mutated familial CJD with the occurrence of a new phenotype not previously described.