LRRK2 and Parkinson disease: Previous studies have revealed that SNCA Hypomethylation, DJ-1, α-syn, Leucine-rich repeat kinase 2 (LRRK2), and acetylcholinesterase (AChE) have the potential to be early biomarkers of PD in exosomes (Fraser et al., 2016; Zhao et al., 2019, 2020; Shim et al., 2021).