NEFL and multiple system atrophy: Since 1) there are conflicting reports and opinions about increase of NfL with disease progression in MSA, 2) there are reports that NfL may predict clinical progression, 3) NfL has been reported as biomarker of disease activity and treatment response in other neurologic disorders, and 4) prior work on this topic is limited to NfL in plasma, further systematic exploration of the role of NfL as marker of disease progression in MSA using serial longitudinal biomarkers in plasma and CSF along with clinical assessments in a carefully phenotyped cohort seemed prudent.20, 21, 38, 39