For example, studies by Abd-Elhadi et al. and ourselves provided evidence showing an increase in the levels of RBC-derived total and oligomeric-α-syn with PD (Abd-Elhadi et al., 2015; Wang et al., 2015); some studies also showed elevations of some post-translationally modified (PTM) α-syn (pY125, pS129, nY39, AGE, and SUMO-1) (Vicente Miranda et al., 2017; Tian et al., 2019) and proteinase K-resistant α-syn (Abd-Elhadi et al., 2015; Tian et al., 2019) in the RBCs of PD patients. This evidence concerns the gene SUMO1 and Parkinson disease.