biostudies-literatureUnknown119Schumacher JGNational Institute of Neurological Disorders and StrokeAligning Science Across Parkinson&apos;sMichael J. Fox Foundation for Parkinson&apos;s Research<h4>Background</h4>α-Synuclein (α-syn) seed amplification assays (SAAs) have shown remarkable potential in diagnosing Parkinson's disease (PD). Using data from the Parkinson's Progression Markers Initiative (PPMI) cohort, we aimed to test whether baseline α-syn seeding activity and α-syn SAA kinetic parameters are associated with disease progression in sporadic PD, LRRK2-associated PD (LRRK2 PD), and GBA-associated PD (GBA PD).<h4>Methods</h4>We analysed 7 years of motor, non-motor, and cognitive assessments and 5 years of dopamine transporter imaging along with baseline α-syn SAA results from 564 PPMI participants (n = 332 sporadic PD, 162 LRRK2 PD, and 70 GBA PD) using linear mixed-effects models, adjusted for potential confounders, to test whether baseline α-syn SAA positivity (n = 315 EBioMedicine105866https://www.ebi.ac.uk/biostudies/studies/S-EPMC12354789biostudies-literatureBaseline α-synuclein seeding activity and disease progression in sporadic and genetic Parkinson's disease in the PPMI cohort.PMC12354789Schwarzschild MAZhang XWatanabe HDijkstra JMSchumacher JGChen XBayati AWang JMacklin EACortese MfalseBaseline α-synuclein seeding activity and disease progression in sporadic and genetic Parkinson's disease in the PPMI cohort.<h4>Background</h4>α-Synuclein (α-syn) seed amplification assays (SAAs) have shown remarkable potential in diagnosing Parkinson's disease (PD). Using data from the Parkinson's Progression Markers Initiative (PPMI) cohort, we aimed to test whether baseline α-syn seeding activity and α-syn SAA kinetic parameters are associated with disease progression in sporadic PD, LRRK2-associated PD (LRRK2 PD), and GBA-associated PD (GBA PD).<h4>Methods</h4>We analysed 7 years of motor, non-motor, and cognitive assessments and 5 years of dopamine transporter imaging along with baseline α-syn SAA results from 564 PPMI participants (n = 332 sporadic PD, 162 LRRK2 PD, and 70 GBA PD) using linear mixed-effects models, adjusted for potential confounders, to test whether baseline α-syn SAA positivity (n = 315 2025-01-01T00:00:00Z2025 Aug2026-04-18T11:21:25.428Z2026-04-07T14:35:39.848ZS-EPMC123547894077392610.1016/j.ebiom.2025.105866