Early Molecular Biomarkers for Differentiating Parkinsonian Syndromes

Identification of Molecular Biomarkers, Including microRNAs and Metabolites, Enabling Early Differentiation of Parkinson's Disease and Atypical Parkinsonian Syndromes in a Prospective Observational Study.

This prospective observational study aims to identify and preliminarily validate molecular biomarkers, including microRNAs and metabolites, for the early differentiation of Parkinson's disease (PD) from atypical parkinsonian syndromes (APS). The study will enroll up to 100 patients with PD, 50 patients with suspected APS, and 50 healthy controls.

Participants will undergo clinical assessments and provide blood, urine, and stool samples at baseline and after 12-18 months of follow-up. Molecular analyses, including microRNA profiling, metabolomics, RNA sequencing (RNA-seq), and microbiome analysis, will be performed to identify disease-specific diagnostic signatures.

The primary objective is to detect differences in molecular profiles among patients with PD, patients with APS, and healthy controls. Secondary objectives include evaluating the diagnostic accuracy of biomarker panels and assessing longitudinal changes in these biomarkers over time.

Although participants will not receive direct therapeutic benefits, the study may contribute to the development of non-invasive tools for the early diagnosis and improved differentiation of parkinsonian disorders.

Inclusion Criteria:

Patients with suspected neurodegenerative parkinsonism in the course of PD or APS, defined according to the 2015 MDS criteria as bradykinesia accompanied by at least one additional symptom: rigidity and/or resting tremor.

Age between 40 and 80 years. Written informed consent for participation in the study. Duration of parkinsonian symptoms shorter than 3 years. Abnormal dopamine transporter single-photon emission computed tomography (DaTscan) result confirming presynaptic dopaminergic neuronal degeneration.

Exclusion Criteria Lack of consent to participate in the study. Secondary or drug-induced parkinsonism. Other central nervous system (CNS) disorders (e.g., neoplastic or vascular processes) that could account for the symptoms.

Active malignancy, infection, or autoimmune inflammatory disease. Severe systemic diseases, including advanced heart failure (New York Heart Association [NYHA] class III-IV), poorly controlled diabetes mellitus, renal failure with glomerular filtration rate (GFR) ≤ 60 mL/min/1.73 m², or hepatic failure.

Presence of a known monogenic mutation causing parkinsonism according to the Online Mendelian Inheritance in Man (OMIM) classification.

Antibiotic therapy or use of probiotics within 3 months prior to the study visit.

Pregnancy or breastfeeding.