PCSK1N and Lewy body dementia: This study provides relevant support for initiating harmonization and standardization of SAA protocols to move the field toward the clinical implementation of SAAs for the biomarker-based diagnosis of DLB.<h4>Classification of evidence</h4>This study provides Class III evidence of variations in the accuracy of CSF α-syn SAA across 4 separate laboratories in distinguishing patients with DLB from healthy controls.