Variably protease‐sensitive prionopathy presenting within ALS/FTD spectrum.

We report clinico‐pathological features of a 65‐year‐old woman and a 56‐year‐old man with a 5‐year clinical history who had clinical and neuropathological characteristics of upper and lower motor neuron disease consistent with amyotrophic lateral sclerosis, and a frontotemporal atrophy pattern in case 2 without TDP‐43 pathology. Instead, spongiform change and pathological prion protein deposits were observed in several brain regions. No prion protein gene mutations were found. Western blot analysis showed a five‐band profile compatible with variably protease‐sensitive prionopathy. We conclude that this disease can display prolonged disease duration and clinico‐pathological features within the ALS/FTLD spectrum. [ABSTRACT FROM AUTHOR]