One of the most widely cited biomarker candidates for PD, DLB and MSA is the α-synuclein protein (α-syn), as the deposition of fibrillar aggregates of α-syn in the cytoplasm of selective populations of neurons (PD and DLB) and oligodendroglia (MSA) can form pathogenic inclusions called Lewy bodies (LB) (Mehra et al., 2019; Porro et al., 2019; Mou et al., 2020). This evidence concerns the gene SNCG and Parkinson disease.