PCSK1N and Parkinson disease: The analysis of this systematic review revealed a pooled sensitivity and specificity for αSyn-SAAs (Figure 3), including all biomatrices and types of assays, in the diagnosis of PD with single-population data of 0.86 (95% CI, 0.85–0.87) and 0.92 (95% CI, 0.91–0.93), respectively.