SNCA and Parkinson disease: Multiple studies identified differentially expressed miRNAs that are directly or indirectly involved in the regulation of key PD genes, including miR-34b and miR-34c (depletion of which led to DJ-1 and PRKN downregulation and SNCA upregulation), miR-205 (its downregulation resulted in LRRK2 upregulation), miR-127-5p and miR-16-5p (both previously shown to regulate GBA1 expression) [129,130,131,132,133].