Alpha synuclein is a member of a family of cytoplasmic proteins found predominantly in the presynaptic nerve terminal of the brain.
Alpha-synuclein misfolding and aggregation is associated with the onset and progression of Parkinson's disease. Excess alpha synuclein aggregates form toxic deposits called Lewy bodies and are found in sporadic Parkinson’s disease and dementia with Lewy bodies. Alpha-synuclein is also a major component of amyloid plaques in Alzheimer’s disease.
Serum alpha-synuclein level has been shown to differentiate Parkinson's disease patients from healthy controls. Alpha-synuclein expression is significantly higher in Parkinson's disease than in healthy controls.
One study found plasma alpha synuclein to have better predictive power than erythrocyte alpha synuclein, with a sensitivity of 80%, specificity of 97.7%, and positive predictive value of 77.8% (Wang et al., Neurodegenerative Diseases, 2019;19(5-6)204-210).
Parkinson's and neurodegenerative movement disorders are heterogeneous in their presentation, course, and outcome, and often present at an undifferentiated stage which may later evolve into established disease. Complex decision-making is required to discriminate between similar presentations and shared features as most movement disorders do not have a single clinical, laboratory, pathological, or radiological feature that serves as a ‘gold standard’ for diagnosis.
