Researchers described an endpoint‑dilution seed amplification assay (SAA) that quantifies α‑synuclein seeds in cerebrospinal fluid with improved precision, enabling measurement of pathological seeding activity rather than binary detection. The methodology enhances tracking of disease burden and could be used as a pharmacodynamic marker in therapeutic trials. The assay showed reproducibility in preclinical validation and early clinical samples and may allow better stratification of Parkinson’s disease patients and monitoring of target engagement for anti‑α‑synuclein therapies. Authors called for validation in larger cohorts and standardization for cross‑site deployment.