Familial spongiform encephalopathy associated with a novel prion protein gene mutation.

Human prion diseases include Creutzfeldt-Jakob disease, Gerstmann-Stráussler-Scheinker disease, fatal familial insomnia, and kuru. Each of these diseases has a specific clinical presentation while spongiform encephalopathy, neuronal loss, and gliosis are their neuropathological hallmarks. We studied a Brazilian family with an autosomal dominant form of dementia. Nine members of the family were affected by a dementia with frontotemporal clinical features, with a mean age at onset of 44.8 +/- 3.8 years and a mean duration of symptoms of 4.2 +/- 2.4 years. Neuropathological examination of 3 patients showed severe spongiform change and neuronal loss in the deep cortical layers and in the putamen, but minimal gliosis in the most severely affected areas. The putamen and cerebellum, but not other areas of the affected brain, displayed prion protein immunoreactivity. A novel prion protein gene mutation causing a nonconservative substitution at codon 183 was identified in 2 neuropathologically confirmed affected individuals (mother and son). The mutation was transmitted in a mendelian fashion to 12 members of the family. Therefore, we identified a novel prion disease variant characterized by an early onset and long duration of the symptoms, severe spongiform change with minimal gliosis, associated with a prion protein gene mutation at codon 183.