Fatal familial insomnia with a mutation at codon 178 of the prion protein gene: first report from Japan.

Fatal familial insomnia (FFI), or familial selective thalamic degeneration with a mutation at codon 178 of the prion protein (PrP) gene, is a rapidly progressive autosomal dominant disease characterized by progressive insomnia, dysautonomia, and myoclonus. We report here the clinical and postmortem findings as well as genomic analysis in a first non-Western case with FFI. This patient also clinically had cognitive impairments such as memory disturbance, delirium, and hallucinations, along with insomnia, dysautonomia, and myoclonus. This case implies a worldwide distribution of FFI and also highlights the need for more aggressive clinical application of genomic analysis of the PrP gene and polysomnographic study in patients with insomnia and cognitive impairments.