Codon 200 mutation of the prion gene: genotype–phenotype correlations
Genetic mutations as a cause of prion diseases are rare. We describe a large family with multiple affected members with the codon E200K prion mutation. To improve understanding of the genotype–phenotype correlations of prion gene mutations, clinical, genetic and neuropathological data were obtained from family members over 15 years. Six patients with the codon E200K mutation and 2 patients without the codon 200 mutation from this family were followed. The 6 patients with the codon 200 mutation had a mean age onset of 58.83 years (SD 7.2; lower 95 % CI 51.0; upper 95 % CI 66.4). The most common symptoms at onset were memory loss, walking difficulties and hallucinations. The most frequent neurological phenomena were a rapidly progressive dementia, eye movement abnormalities and ataxia. The mean duration of onset of symptoms to death was 3.9 months (SD 1.1; lower 95 % CI 2.8; upper 95 % CI 5.1). Two male patients developed neurodegenerative disorders unrelated to the prion codon 200 mutation: progressive supranuclear palsy and olivopontocerebellar degeneration. Their mean survival was 96 months (SD 33.9; p < 0.0001). Individuals from families with the prion codon 200 mutation may have a rapidly progressive dementia. Members of families with inherited prion mutations may be at risk of other neurodegenerative disorders unrelated to the prion mutation.