Mutation in the prion protein gene at codon 232 in Japanese patients with Creutzfeldt-Jakob disease: a clinicopathological, immunohistochemical and transmission study

We describe the clinical, neuropathological, immunohistochemical and transmission findings in three patients with Creutzfeldt-Jakob disease (CJD) with a substitution from methionine to arginine at codon 232 (M232R) in the prion protein (PrP) gene. The patients with M232R presented clinically with rapidly progressive dementia, myoclonus, and periodic synchronous discharges in the electroencephalogram. These findings were mostly consistent with those for sporadic CJD. All patients reached the stage of akinetic mutism between 2 and 6 months, and died between 4 and 24 months after the onset of the disease. Histopathological examination revealed spongiform changes, neuronal loss and severe astrocytosis. Immunohistochemical staining for PrP showed diffuse gray matter staining, including synaptic structures. However, no plaque-type PrP deposition was observed in the affected brain tissue sections. The brain homogenates from two patients were successfully transmitted to experimental animals. Since the same mutation was not found in 100 healthy control individuals, the mutation might be associated with the disease. The clinicopathological and experimental transmission studies of CJD patients with this PrP gene mutation may thus help us to determine both phenotypic variations and the potential infectivities in different forms of prion diseases.