The recent finding of a positive correlation between neurofilament light chain level in cerebrospinal fluid and disease progression rate in progressive supranuclear palsy, Alzheimer’s disease, dementia with Lewy bodies and frontotemporal lobar degeneration [1, 56] is a promising start to understand the underlying pathophysiology, and to identify accurate biomarkers and genetic modifiers of rapid progressors in neurodegenerative diseases such as fulminant CBD. The gene discussed is NEFL; the disease is Classical progressive supranuclear palsy.