Protracted course progressive supranuclear palsy.

We propose a protracted course subtype of PSP (PC-PSP) based on clinical or neuropathological criteria in two cases with anatomically restricted PSP pathology, and very long DD and slower clinical progression in the other two cases. The presence of the rs564309-C allele may influence the protracted disease course. Crystallizing the concept of PC-PSP is important to further understand the pathobiology of tauopathies in line with current hypotheses of protein misfolding, seeding activity, and propagation.