Detection of A-synuclein Aggregate As Biomarker in Diagnosing Parkinson's Disease At Early Stage by Using Protein Misfolding Cyclic Amplification (PMCA)

This will be an observational study aiming to develop the protein misfolding cyclic amplification (PMCA) technology that detects minute amounts of αSyn aggregates circulating in cerebrospinal fluid (CSF) as a novel assay with high sensitivity and specificity for the early diagnosis of PD. To achieve this goal, we will apply the PMCA to detect the αSyn aggregates in the CSF samples acquired from a discovery cohort that consist of well-characterized early PD patients (disease duration ≤1 year and Hoehn and Yahr Stage I, and DAT-PET and FDG-PET meet the imaging features of PD, n=75) and gender, age-matched healthy controls (n=38). Furthermore, we will confirm the findings in a separate confirmatory cohort with well-characterized early PD patients (disease duration ≤1 year and Hoehn and Yahr Stage I, and DAT-PET and FDG-PET meet the imaging features of PD, n=75), early multiple system atrophy (MSA) patients (disease duration ≤1 year, n=38), early progressive supranuclear palsy (PSP) patients (disease duration ≤1 year, n=38) and age-matched healthy controls (n=38). The sensitivity, specificity, positive predictive value, negative predictive value, and area under curve of the PMCA for the early diagnosis of PD will be calculated in the discovery cohort and be confirmed in the confirmatory cohort, respectively. In addition, the clinical characteristics, including motor and nonmotor symptoms of early PD, MSA and PSP patients in the two cohort will be comprehensively assessed at baseline and during followed-up. To assess the value of the PMCA technology in the evaluation of the disease severity and progress, we will perform the partial correlation analysis between clinical features of early PD patients and the PMCA T50 defined as the time needed to reach 50% of the maximum aggregation.

Misfolded αSyn aggregates have the potential to serve as a biomarker for early PD. The PMCA technology could detect small quantities of misfolded αSyn aggregates by taking advantage of their ability to nucleate further aggregation, enabling a very high amplification of the signal. This study examines the effectiveness of using the PMCA as a novel technique for discriminating early PD from gender, age-matched healthy controls and other early parkinsonian disorders (MSA, PSP) by detecting small misfolded αSyn aggregates in CSF.