Objective: To detect α-synuclein (aSyn) in tear fluid and to evaluate the clinical characteristics of aSyn-positive patients.
Background: Parkinson’s disease (PD) is an α-synucleinopathy. Pathological α-synuclein (aSyn) is detectable in peripheral tissues and fluids. The diagnostic utility of tear fluid as a minimally invasive source for aSyn seed detection remains unclear.
Method: Tear fluid samples were collected bilaterally using Schirmer test strips. Tear fluid was extracted from Schirmer test strips using phosphate-buffered saline. Extracted aSyn was analyzed using the real-time quaking-induced conversion assay. ThT fluorescence was measured every 15 min using excitation and emission wavelengths of 450 nm and 480 nm, respectively. A reaction was considered positive when ThT fluorescence exceeded 20,000 arbitrary units within 200 cycles, per established criteria. All analyses were performed using SPSS v.30. Ninety-five percent confidence intervals were calculated using the Clopper–Pearson exact method in EZR.
Results: The aSyn seeding amplification assay (α-syn SAA) detected aSyn seeding activity in tear fluid collected via Schirmer test strips. The assay showed 52.7% sensitivity and 100% specificity. Moreover, patients who were α-syn SAA-positive had higher Movement Disorder Society–Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) part III scores than the patients that were α-syn SAA-negative, suggesting correlation with clinical disease severity (P <0.05). Multivariable logistic regression assessed the relationship between α-syn SAA and MDS-UPDRS part III scores, adjusting for age, sex, and disease duration (P <0.05).
Conclusion: aSyn seeding activity was detected in tear fluid from patients with PD yet absent in disease controls. Further studies in related synucleinopathies and early or prodromal PD are needed to validate these findings and evaluate the diagnostic sensitivity and specificity of this tear-based assay.
To cite this abstract in AMA style:
A. Kakimoto, K. Satoh, T. Tsukahara-Kawamura, Y. Tsuboi. Real-Time Quaking-Induced Conversion Detection of Tear Fluid α-Synuclein as a Potential Biomarker for Parkinson’s Disease [abstract]. Mov Disord. 2026; 41 (suppl 1). https://www.mdsabstracts.org/abstract/real-time-quaking-induced-conversion-detection-of-tear-fluid-%ce%b1-synuclein-as-a-potential-biomarker-for-parkinsons-disease/. Accessed October 1, 2026.« Back to 2026 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/real-time-quaking-induced-conversion-detection-of-tear-fluid-%ce%b1-synuclein-as-a-potential-biomarker-for-parkinsons-disease/