SNCA and Parkinson disease: It should be noted that miR-7 is enriched in the brain and has been found to inhibit the expression of SNCA, there have been a few studies on miR-7 as a biomarker for PD diagnosis in recent years (Zhou et al., 2016; Li et al., 2019; Starhof et al., 2019; Cressatti et al., 2020; Ravanidis et al., 2020).