In iPSC-based neuronal models of PD, NPCs [77], cortical neurons [55], and dopaminergic neurons [81] from SNCA mutant or triplication PD patients, as well as NESCs from LRRK2 G2019S PD patients [75] and dopaminergic neurons from VPS35 [73], displayed reduced ΔΨm. Here, LRRK2 is linked to Parkinson disease.