NEFL and supranuclear palsy, progressive, 1: Another biomarker purposed is Neurofilament light chain (Nfl), an unspecific marker of axonal degeneration, which has high accuracy in differentiating PD from atypical parkinsonisms [MSA, progressive sopranuclear palsy (PSP) and cortico-basal degeneration (CBD)], but not in discriminating among different subtypes of atypical parkinsonisms [26].