NCT04724941 (Prodromal Alpha-Synuclein Screening in Parkinson's Disease Study) is an observational clinical trial designed to identify individuals in the prodromal stage of Parkinson's disease using alpha-synuclein seed amplification assays. The study aims to characterize risk marker profiles in at-risk populations, enabling early detection and potential intervention before manifest motor symptoms develop [1].
This mechanistic page integrates the trial's approach with the underlying biology of alpha-synuclein pathology propagation, prodromal biomarkers, and the emerging role of seed amplification assays in early PD detection.
| Attribute | Details |
|---|---|
| Trial ID | NCT04724941 |
| Status | Recruiting |
| Enrollment | 2,000 participants (estimated) |
| Sponsor | University Hospital Schleswig-Holstein |
| Collaborators | UCB Biopharma SRL; University of Kiel |
| Location | Kiel, Germany |
| Start Date | June 2021 |
| Completion | December 2027 |
| Study Type | Observational |
| Primary Outcome | Risk marker profile |
Parkinson's disease is characterized by a long prodromal period during which pathological changes occur but clinical motor symptoms have not yet manifested. This window represents a critical opportunity for:
The prodromal phase of PD is characterized by several non-motor features that precede motor symptoms by years to decades:
Alpha-synuclein (α-syn) is a 140-amino acid protein encoded by the SNCA gene that plays important roles in synaptic vesicle trafficking and neurotransmitter release. In its native state, α-syn exists as an intrinsically disordered monomer that transiently interacts with lipid membranes [2].
In PD, α-syn undergoes a conformational change from native monomer to misfolded oligomers and fibrils that accumulate as Lewy bodies and Lewy neurites. This conversion is templated by pathological seeds—a process known as seeding 2.
The key steps in pathological α-syn conversion:
The pathological α-syn species exhibit prion-like properties, able to template the conversion of normal endogenous α-syn in recipient cells. This template-directed misfolding drives the spread of pathology throughout the nervous system 3.
Key propagation mechanisms:
See Alpha-Synuclein Propagation Models for detailed mechanisms.
Seed amplification assays are ultrasensitive detection methods that exploit the prion-like property of misfolded α-syn. These assays can detect pathological seeds at concentrations as low as 10⁻¹⁵ to 10⁻¹⁶ M 4.
RT-QuIC detects α-syn seeds by their ability to template the conversion of recombinant α-syn monomer into amyloid fibrils:
Performance characteristics:
PMCA uses sonication cycles to amplify α-syn seeds in a manner analogous to PCR:
| Method | Target | Sensitivity | Sample Type | Clinical Use |
|---|---|---|---|---|
| SAA | Pathological seeds | 85-95% | CSF, Blood | Diagnostic, Prodromal |
| Total α-syn | All α-syn | Variable | CSF, Blood | Research |
| pSer129 | Phosphorylated α-syn | ~90% | CSF, Blood | Pathological confirmation |
| Oligomers | Toxic oligomers | Moderate | CSF | Research |
CSF provides direct access to the central nervous system and is the most validated sample type for α-syn detection:
Advantages:
Limitations:
Key CSF biomarkers:
Blood-based testing offers significant advantages for population screening:
Advantages:
Challenges:
Emerging approaches:
The trial aims to leverage both CSF and blood-based SAA approaches to characterize the "risk marker profile" in prodromal individuals. This comprehensive approach will:
Early detection through seed amplification enables several intervention strategies:
| Strategy | Approach | Timing |
|---|---|---|
| Neuroprotection | Protect surviving neurons | Prodromal/Early |
| Disease modification | Halt seed propagation | Prodromal |
| Symptomatic | Dopaminergic therapy | Manifest |
| Preventive | Lifestyle modifications | At-risk |
SAA-positive prodromal individuals represent ideal participants for disease-modifying therapy trials:
Advantages:
See Alpha-Synuclein Seed Kinetic Staging for kinetic stratification approaches.
NCT04724941: Prodromal Alpha-Synuclein Screening in Parkinson's Disease Study. ↩︎
Sato K, et al. Propagation of α-synuclein pathology. Neuron. 2023. ↩︎