Importantly, accumulation of oxidized DA/DA-Q represents a key phenotype developing over time in human iPSC-derived DAergic neurons from genetic PD forms related to mitochondrial (PARKIN, PINK1, DJ-1) and endolysosomal pathways (LRRK2, GBA1) or sporadic PD (Burbulla et al., 2017, 2019; Ysselstein et al., 2019; Laperle et al., 2020). This evidence concerns the gene LRRK2 and Parkinson disease.