This mutation was found by Liberski et al. in a case diagnosed earlier as olivopontocerebellar degeneration and provided by Prof. Maria Barcikowska, Warsaw. The disease started in the fifth decade of life and lasted for 6 years. It manifested itself as spastic paraparesis and dementia. Numerous PrP plaques were visible in the cerebral and cerebellar cortex and in the subcortical nuclei; in the substantia nigra Lewy bodies were occasionally seen.