Although the patient had no family history of CJD, genetic CJD was diagnosed according to extensive hyperintensities in the bilateral cortices on diffusion-weighted magnetic resonance images, positive tau protein and 14-3-3 protein in the cerebrospinal fluid and a V180I mutation with methionine homozygosity at codon 129 by prion protein gene analysis. The gene discussed is MAPT; the disease is Creutzfeldt Jacob disease.