SYN1 and Parkinson disease: We stratified the subjects based on the α-Syn seed amplification assay (SAA) combined with α-syn-Protein misfolding cyclic amplification (PMCA) assay results and categorized patients with no detectable CSF α-Syn aggregates into the Syn0 group, and those with detectable CSF α-Syn aggregates consistent with PD into the Syn1 group (hereafter, the two CSF α-Syn aggregation states will be referred to as α-Syn0 and α-Syn1, respectively).