NEFL and multiple system atrophy: One subject (#3020) was unanimously detected as negative αSyn-SAA by all three groups, and demonstrated rapid motor progression (UPDRS Part 3 increased by + 25 from BL to Y3), elevated SCOPA-AUT score of 17, and elevated baseline CSF NfL (166.4 pg/ml), suggesting possible MSA or alternative diagnosis to PD.