ATXN3 and neurodegenerative disease: In fact, while the correlation between Nf levels in the extracellular compartment of the brain and the cerebrospinal fluid (CSF) is yet unknown, a close correlation between Nf levels in the CSF and the peripheral blood has been established for several neurodegenerative diseases (Bacioglu et al, 2016; Wilke et al, 2016, 2019; Khalil et al, 2018; Gaetani et al, 2019), including also SCA3 (Li et al, 2019).