Evidence map›Paper›PMID 42706613›Full record

ArticleJournal of Parkinson's disease2026

Detection of α-synuclein seeding activity in tear fluid as a candidate biomarker for Parkinson's disease.

Asako Kakimoto, Katsuya Satoh, Tomoko Tsukahara-Kawamura, Yoshio Tsuboi

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Article in Journal of Parkinson's disease, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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5 · Who and what money

Authors and funding

4 authors.

Asako KakimotoDepartment of Neurology, Juntendo University School of Medicine, Juntendo University, Bunkyo-ku, Japan.ORCID 0009-0004-3419-164X
Katsuya SatohDepartment of Health Sciences, Unit of Medical and Dental Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.ORCID 0000-0001-8007-8710
Tomoko Tsukahara-KawamuraDepartment of Ophthalmology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.ORCID 0000-0001-5651-9790
Yoshio TsuboiDepartment of Neurology, Long-term Observation Research, Juntendo University, Tokyo, Japan.ORCID 0000-0002-6758-0981

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

BackgroundParkinson's disease (PD) is an α-synucleinopathy, and pathological α-synuclein (α-Syn) is detectable in peripheral tissues and fluids. However, the diagnostic utility of tear fluid as a minimally invasive source for α-Syn seed detection remains unclear. We aimed to detect α-Syn seeds in tear fluid and evaluate the clinical characteristics of α-Syn-positive patients.MethodsTear fluid was collected bilaterally using Schirmer strips. The α-Syn seeding amplification assay (αSynSAA) was performed using the real-time quaking-induced conversion (RT-QuIC) protocol. We analyzed 55 patients with PD and 40 control participants.ResultsThe αSynSAA revealed α- synuclein seeding activity in tear fluid, showing 52.7% sensitivity and 100% specificity. αSyn SAA-positive patients had higher Movement Disorder Society-Unified Parkinsons Disease Rating Scale part III scores than αSyn SAA-negative patients. α-Syn seeding activity was detected in tear fluid from some patients with PD but not in disease controls.ConclusionThis study demonstrates the feasibility of αSynSAA analysis in tear fluid, highlighting its potential as a novel substrate for biomarker development. Further studies in related synucleinopathies and in early or prodromal PD are needed to validate these findings and assess the diagnostic performance of this tear-based assay.

Indexed as

Parkinson's diseaseRT-QuICtear biomarkerstear fluidα-Syn seeding amplification assays (αSynSAA)α-synuclein (α-Syn)

Identifiers

PMID42706613
PMCPMC13550234

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